We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
Use of uninitialised variable in pip/commands/list.py
The BestVersionAlreadyInstalled case of find_packages_latests_versions() does not set the variable remote_version_parsed, thus it could be used uninitialised.


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `pip/commands/list.py`
Content:
```
1 from __future__ import absolute_import
2 
3 import logging
4 import warnings
5 
6 from pip.basecommand import Command
7 from pip.exceptions import DistributionNotFound, BestVersionAlreadyInstalled
8 from pip.index import PackageFinder
9 from pip.req import InstallRequirement
10 from pip.utils import get_installed_distributions, dist_is_editable
11 from pip.utils.deprecation import RemovedInPip17Warning
12 from pip.cmdoptions import make_option_group, index_group
13 
14 
15 logger = logging.getLogger(__name__)
16 
17 
18 class ListCommand(Command):
19     """
20     List installed packages, including editables.
21 
22     Packages are listed in a case-insensitive sorted order.
23     """
24     name = 'list'
25     usage = """
26       %prog [options]"""
27     summary = 'List installed packages.'
28 
29     def __init__(self, *args, **kw):
30         super(ListCommand, self).__init__(*args, **kw)
31 
32         cmd_opts = self.cmd_opts
33 
34         cmd_opts.add_option(
35             '-o', '--outdated',
36             action='store_true',
37             default=False,
38             help='List outdated packages (excluding editables)')
39         cmd_opts.add_option(
40             '-u', '--uptodate',
41             action='store_true',
42             default=False,
43             help='List uptodate packages (excluding editables)')
44         cmd_opts.add_option(
45             '-e', '--editable',
46             action='store_true',
47             default=False,
48             help='List editable projects.')
49         cmd_opts.add_option(
50             '-l', '--local',
51             action='store_true',
52             default=False,
53             help=('If in a virtualenv that has global access, do not list '
54                   'globally-installed packages.'),
55         )
56 
57         cmd_opts.add_option(
58             '--pre',
59             action='store_true',
60             default=False,
61             help=("Include pre-release and development versions. By default, "
62                   "pip only finds stable versions."),
63         )
64 
65         index_opts = make_option_group(index_group, self.parser)
66 
67         self.parser.insert_option_group(0, index_opts)
68         self.parser.insert_option_group(0, cmd_opts)
69 
70     def _build_package_finder(self, options, index_urls, session):
71         """
72         Create a package finder appropriate to this list command.
73         """
74         return PackageFinder(
75             find_links=options.find_links,
76             index_urls=index_urls,
77             allow_external=options.allow_external,
78             allow_unverified=options.allow_unverified,
79             allow_all_external=options.allow_all_external,
80             allow_all_prereleases=options.pre,
81             process_dependency_links=options.process_dependency_links,
82             session=session,
83         )
84 
85     def run(self, options, args):
86         if options.outdated:
87             self.run_outdated(options)
88         elif options.uptodate:
89             self.run_uptodate(options)
90         elif options.editable:
91             self.run_editables(options)
92         else:
93             self.run_listing(options)
94 
95     def run_outdated(self, options):
96         for dist, remote_version_raw, remote_version_parsed in \
97                 self.find_packages_latests_versions(options):
98             if remote_version_parsed > dist.parsed_version:
99                 logger.info(
100                     '%s (Current: %s Latest: %s)',
101                     dist.project_name, dist.version, remote_version_raw,
102                 )
103 
104     def find_packages_latests_versions(self, options):
105         index_urls = [options.index_url] + options.extra_index_urls
106         if options.no_index:
107             logger.info('Ignoring indexes: %s', ','.join(index_urls))
108             index_urls = []
109 
110         if options.use_mirrors:
111             warnings.warn(
112                 "--use-mirrors has been deprecated and will be removed in the "
113                 "future. Explicit uses of --index-url and/or --extra-index-url"
114                 " is suggested.",
115                 RemovedInPip17Warning,
116             )
117 
118         if options.mirrors:
119             warnings.warn(
120                 "--mirrors has been deprecated and will be removed in the "
121                 "future. Explicit uses of --index-url and/or --extra-index-url"
122                 " is suggested.",
123                 RemovedInPip17Warning,
124             )
125             index_urls += options.mirrors
126 
127         dependency_links = []
128         for dist in get_installed_distributions(local_only=options.local):
129             if dist.has_metadata('dependency_links.txt'):
130                 dependency_links.extend(
131                     dist.get_metadata_lines('dependency_links.txt'),
132                 )
133 
134         with self._build_session(options) as session:
135             finder = self._build_package_finder(options, index_urls, session)
136             finder.add_dependency_links(dependency_links)
137 
138             installed_packages = get_installed_distributions(
139                 local_only=options.local,
140                 include_editables=False,
141             )
142             for dist in installed_packages:
143                 req = InstallRequirement.from_line(dist.key, None)
144                 try:
145                     link = finder.find_requirement(req, True)
146 
147                     # If link is None, means installed version is most
148                     # up-to-date
149                     if link is None:
150                         continue
151                 except DistributionNotFound:
152                     continue
153                 except BestVersionAlreadyInstalled:
154                     remote_version = req.installed_version
155                 else:
156                     # It might be a good idea that link or finder had a public
157                     # method that returned version
158                     remote_version = finder._link_package_versions(
159                         link, req.name
160                     )[0]
161                     remote_version_raw = remote_version[2]
162                     remote_version_parsed = remote_version[0]
163                 yield dist, remote_version_raw, remote_version_parsed
164 
165     def run_listing(self, options):
166         installed_packages = get_installed_distributions(
167             local_only=options.local,
168         )
169         self.output_package_listing(installed_packages)
170 
171     def run_editables(self, options):
172         installed_packages = get_installed_distributions(
173             local_only=options.local,
174             editables_only=True,
175         )
176         self.output_package_listing(installed_packages)
177 
178     def output_package_listing(self, installed_packages):
179         installed_packages = sorted(
180             installed_packages,
181             key=lambda dist: dist.project_name.lower(),
182         )
183         for dist in installed_packages:
184             if dist_is_editable(dist):
185                 line = '%s (%s, %s)' % (
186                     dist.project_name,
187                     dist.version,
188                     dist.location,
189                 )
190             else:
191                 line = '%s (%s)' % (dist.project_name, dist.version)
192             logger.info(line)
193 
194     def run_uptodate(self, options):
195         uptodate = []
196         for dist, remote_version_raw, remote_version_parsed in \
197                 self.find_packages_latests_versions(options):
198             if dist.parsed_version == remote_version_parsed:
199                 uptodate.append(dist)
200         self.output_package_listing(uptodate)
201
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/pip/commands/list.py b/pip/commands/list.py
--- a/pip/commands/list.py
+++ b/pip/commands/list.py
@@ -4,7 +4,7 @@
 import warnings
 
 from pip.basecommand import Command
-from pip.exceptions import DistributionNotFound, BestVersionAlreadyInstalled
+from pip.exceptions import DistributionNotFound
 from pip.index import PackageFinder
 from pip.req import InstallRequirement
 from pip.utils import get_installed_distributions, dist_is_editable
@@ -150,8 +150,6 @@
                         continue
                 except DistributionNotFound:
                     continue
-                except BestVersionAlreadyInstalled:
-                    remote_version = req.installed_version
                 else:
                     # It might be a good idea that link or finder had a public
                     # method that returned version

{"golden_diff": "diff --git a/pip/commands/list.py b/pip/commands/list.py\n--- a/pip/commands/list.py\n+++ b/pip/commands/list.py\n@@ -4,7 +4,7 @@\n import warnings\n \n from pip.basecommand import Command\n-from pip.exceptions import DistributionNotFound, BestVersionAlreadyInstalled\n+from pip.exceptions import DistributionNotFound\n from pip.index import PackageFinder\n from pip.req import InstallRequirement\n from pip.utils import get_installed_distributions, dist_is_editable\n@@ -150,8 +150,6 @@\n                         continue\n                 except DistributionNotFound:\n                     continue\n-                except BestVersionAlreadyInstalled:\n-                    remote_version = req.installed_version\n                 else:\n                     # It might be a good idea that link or finder had a public\n                     # method that returned version\n", "issue": "Use of uninitialised variable in pip/commands/list.py\nThe BestVersionAlreadyInstalled case of find_packages_latests_versions() does not set the variable remote_version_parsed, thus it could be used uninitialised.\n\n", "before_files": [{"content": "from __future__ import absolute_import\n\nimport logging\nimport warnings\n\nfrom pip.basecommand import Command\nfrom pip.exceptions import DistributionNotFound, BestVersionAlreadyInstalled\nfrom pip.index import PackageFinder\nfrom pip.req import InstallRequirement\nfrom pip.utils import get_installed_distributions, dist_is_editable\nfrom pip.utils.deprecation import RemovedInPip17Warning\nfrom pip.cmdoptions import make_option_group, index_group\n\n\nlogger = logging.getLogger(__name__)\n\n\nclass ListCommand(Command):\n    \"\"\"\n    List installed packages, including editables.\n\n    Packages are listed in a case-insensitive sorted order.\n    \"\"\"\n    name = 'list'\n    usage = \"\"\"\n      %prog [options]\"\"\"\n    summary = 'List installed packages.'\n\n    def __init__(self, *args, **kw):\n        super(ListCommand, self).__init__(*args, **kw)\n\n        cmd_opts = self.cmd_opts\n\n        cmd_opts.add_option(\n            '-o', '--outdated',\n            action='store_true',\n            default=False,\n            help='List outdated packages (excluding editables)')\n        cmd_opts.add_option(\n            '-u', '--uptodate',\n            action='store_true',\n            default=False,\n            help='List uptodate packages (excluding editables)')\n        cmd_opts.add_option(\n            '-e', '--editable',\n            action='store_true',\n            default=False,\n            help='List editable projects.')\n        cmd_opts.add_option(\n            '-l', '--local',\n            action='store_true',\n            default=False,\n            help=('If in a virtualenv that has global access, do not list '\n                  'globally-installed packages.'),\n        )\n\n        cmd_opts.add_option(\n            '--pre',\n            action='store_true',\n            default=False,\n            help=(\"Include pre-release and development versions. By default, \"\n                  \"pip only finds stable versions.\"),\n        )\n\n        index_opts = make_option_group(index_group, self.parser)\n\n        self.parser.insert_option_group(0, index_opts)\n        self.parser.insert_option_group(0, cmd_opts)\n\n    def _build_package_finder(self, options, index_urls, session):\n        \"\"\"\n        Create a package finder appropriate to this list command.\n        \"\"\"\n        return PackageFinder(\n            find_links=options.find_links,\n            index_urls=index_urls,\n            allow_external=options.allow_external,\n            allow_unverified=options.allow_unverified,\n            allow_all_external=options.allow_all_external,\n            allow_all_prereleases=options.pre,\n            process_dependency_links=options.process_dependency_links,\n            session=session,\n        )\n\n    def run(self, options, args):\n        if options.outdated:\n            self.run_outdated(options)\n        elif options.uptodate:\n            self.run_uptodate(options)\n        elif options.editable:\n            self.run_editables(options)\n        else:\n            self.run_listing(options)\n\n    def run_outdated(self, options):\n        for dist, remote_version_raw, remote_version_parsed in \\\n                self.find_packages_latests_versions(options):\n            if remote_version_parsed > dist.parsed_version:\n                logger.info(\n                    '%s (Current: %s Latest: %s)',\n                    dist.project_name, dist.version, remote_version_raw,\n                )\n\n    def find_packages_latests_versions(self, options):\n        index_urls = [options.index_url] + options.extra_index_urls\n        if options.no_index:\n            logger.info('Ignoring indexes: %s', ','.join(index_urls))\n            index_urls = []\n\n        if options.use_mirrors:\n            warnings.warn(\n                \"--use-mirrors has been deprecated and will be removed in the \"\n                \"future. Explicit uses of --index-url and/or --extra-index-url\"\n                \" is suggested.\",\n                RemovedInPip17Warning,\n            )\n\n        if options.mirrors:\n            warnings.warn(\n                \"--mirrors has been deprecated and will be removed in the \"\n                \"future. Explicit uses of --index-url and/or --extra-index-url\"\n                \" is suggested.\",\n                RemovedInPip17Warning,\n            )\n            index_urls += options.mirrors\n\n        dependency_links = []\n        for dist in get_installed_distributions(local_only=options.local):\n            if dist.has_metadata('dependency_links.txt'):\n                dependency_links.extend(\n                    dist.get_metadata_lines('dependency_links.txt'),\n                )\n\n        with self._build_session(options) as session:\n            finder = self._build_package_finder(options, index_urls, session)\n            finder.add_dependency_links(dependency_links)\n\n            installed_packages = get_installed_distributions(\n                local_only=options.local,\n                include_editables=False,\n            )\n            for dist in installed_packages:\n                req = InstallRequirement.from_line(dist.key, None)\n                try:\n                    link = finder.find_requirement(req, True)\n\n                    # If link is None, means installed version is most\n                    # up-to-date\n                    if link is None:\n                        continue\n                except DistributionNotFound:\n                    continue\n                except BestVersionAlreadyInstalled:\n                    remote_version = req.installed_version\n                else:\n                    # It might be a good idea that link or finder had a public\n                    # method that returned version\n                    remote_version = finder._link_package_versions(\n                        link, req.name\n                    )[0]\n                    remote_version_raw = remote_version[2]\n                    remote_version_parsed = remote_version[0]\n                yield dist, remote_version_raw, remote_version_parsed\n\n    def run_listing(self, options):\n        installed_packages = get_installed_distributions(\n            local_only=options.local,\n        )\n        self.output_package_listing(installed_packages)\n\n    def run_editables(self, options):\n        installed_packages = get_installed_distributions(\n            local_only=options.local,\n            editables_only=True,\n        )\n        self.output_package_listing(installed_packages)\n\n    def output_package_listing(self, installed_packages):\n        installed_packages = sorted(\n            installed_packages,\n            key=lambda dist: dist.project_name.lower(),\n        )\n        for dist in installed_packages:\n            if dist_is_editable(dist):\n                line = '%s (%s, %s)' % (\n                    dist.project_name,\n                    dist.version,\n                    dist.location,\n                )\n            else:\n                line = '%s (%s)' % (dist.project_name, dist.version)\n            logger.info(line)\n\n    def run_uptodate(self, options):\n        uptodate = []\n        for dist, remote_version_raw, remote_version_parsed in \\\n                self.find_packages_latests_versions(options):\n            if dist.parsed_version == remote_version_parsed:\n                uptodate.append(dist)\n        self.output_package_listing(uptodate)\n", "path": "pip/commands/list.py"}], "after_files": [{"content": "from __future__ import absolute_import\n\nimport logging\nimport warnings\n\nfrom pip.basecommand import Command\nfrom pip.exceptions import DistributionNotFound\nfrom pip.index import PackageFinder\nfrom pip.req import InstallRequirement\nfrom pip.utils import get_installed_distributions, dist_is_editable\nfrom pip.utils.deprecation import RemovedInPip17Warning\nfrom pip.cmdoptions import make_option_group, index_group\n\n\nlogger = logging.getLogger(__name__)\n\n\nclass ListCommand(Command):\n    \"\"\"\n    List installed packages, including editables.\n\n    Packages are listed in a case-insensitive sorted order.\n    \"\"\"\n    name = 'list'\n    usage = \"\"\"\n      %prog [options]\"\"\"\n    summary = 'List installed packages.'\n\n    def __init__(self, *args, **kw):\n        super(ListCommand, self).__init__(*args, **kw)\n\n        cmd_opts = self.cmd_opts\n\n        cmd_opts.add_option(\n            '-o', '--outdated',\n            action='store_true',\n            default=False,\n            help='List outdated packages (excluding editables)')\n        cmd_opts.add_option(\n            '-u', '--uptodate',\n            action='store_true',\n            default=False,\n            help='List uptodate packages (excluding editables)')\n        cmd_opts.add_option(\n            '-e', '--editable',\n            action='store_true',\n            default=False,\n            help='List editable projects.')\n        cmd_opts.add_option(\n            '-l', '--local',\n            action='store_true',\n            default=False,\n            help=('If in a virtualenv that has global access, do not list '\n                  'globally-installed packages.'),\n        )\n\n        cmd_opts.add_option(\n            '--pre',\n            action='store_true',\n            default=False,\n            help=(\"Include pre-release and development versions. By default, \"\n                  \"pip only finds stable versions.\"),\n        )\n\n        index_opts = make_option_group(index_group, self.parser)\n\n        self.parser.insert_option_group(0, index_opts)\n        self.parser.insert_option_group(0, cmd_opts)\n\n    def _build_package_finder(self, options, index_urls, session):\n        \"\"\"\n        Create a package finder appropriate to this list command.\n        \"\"\"\n        return PackageFinder(\n            find_links=options.find_links,\n            index_urls=index_urls,\n            allow_external=options.allow_external,\n            allow_unverified=options.allow_unverified,\n            allow_all_external=options.allow_all_external,\n            allow_all_prereleases=options.pre,\n            process_dependency_links=options.process_dependency_links,\n            session=session,\n        )\n\n    def run(self, options, args):\n        if options.outdated:\n            self.run_outdated(options)\n        elif options.uptodate:\n            self.run_uptodate(options)\n        elif options.editable:\n            self.run_editables(options)\n        else:\n            self.run_listing(options)\n\n    def run_outdated(self, options):\n        for dist, remote_version_raw, remote_version_parsed in \\\n                self.find_packages_latests_versions(options):\n            if remote_version_parsed > dist.parsed_version:\n                logger.info(\n                    '%s (Current: %s Latest: %s)',\n                    dist.project_name, dist.version, remote_version_raw,\n                )\n\n    def find_packages_latests_versions(self, options):\n        index_urls = [options.index_url] + options.extra_index_urls\n        if options.no_index:\n            logger.info('Ignoring indexes: %s', ','.join(index_urls))\n            index_urls = []\n\n        if options.use_mirrors:\n            warnings.warn(\n                \"--use-mirrors has been deprecated and will be removed in the \"\n                \"future. Explicit uses of --index-url and/or --extra-index-url\"\n                \" is suggested.\",\n                RemovedInPip17Warning,\n            )\n\n        if options.mirrors:\n            warnings.warn(\n                \"--mirrors has been deprecated and will be removed in the \"\n                \"future. Explicit uses of --index-url and/or --extra-index-url\"\n                \" is suggested.\",\n                RemovedInPip17Warning,\n            )\n            index_urls += options.mirrors\n\n        dependency_links = []\n        for dist in get_installed_distributions(local_only=options.local):\n            if dist.has_metadata('dependency_links.txt'):\n                dependency_links.extend(\n                    dist.get_metadata_lines('dependency_links.txt'),\n                )\n\n        with self._build_session(options) as session:\n            finder = self._build_package_finder(options, index_urls, session)\n            finder.add_dependency_links(dependency_links)\n\n            installed_packages = get_installed_distributions(\n                local_only=options.local,\n                include_editables=False,\n            )\n            for dist in installed_packages:\n                req = InstallRequirement.from_line(dist.key, None)\n                try:\n                    link = finder.find_requirement(req, True)\n\n                    # If link is None, means installed version is most\n                    # up-to-date\n                    if link is None:\n                        continue\n                except DistributionNotFound:\n                    continue\n                else:\n                    # It might be a good idea that link or finder had a public\n                    # method that returned version\n                    remote_version = finder._link_package_versions(\n                        link, req.name\n                    )[0]\n                    remote_version_raw = remote_version[2]\n                    remote_version_parsed = remote_version[0]\n                yield dist, remote_version_raw, remote_version_parsed\n\n    def run_listing(self, options):\n        installed_packages = get_installed_distributions(\n            local_only=options.local,\n        )\n        self.output_package_listing(installed_packages)\n\n    def run_editables(self, options):\n        installed_packages = get_installed_distributions(\n            local_only=options.local,\n            editables_only=True,\n        )\n        self.output_package_listing(installed_packages)\n\n    def output_package_listing(self, installed_packages):\n        installed_packages = sorted(\n            installed_packages,\n            key=lambda dist: dist.project_name.lower(),\n        )\n        for dist in installed_packages:\n            if dist_is_editable(dist):\n                line = '%s (%s, %s)' % (\n                    dist.project_name,\n                    dist.version,\n                    dist.location,\n                )\n            else:\n                line = '%s (%s)' % (dist.project_name, dist.version)\n            logger.info(line)\n\n    def run_uptodate(self, options):\n        uptodate = []\n        for dist, remote_version_raw, remote_version_parsed in \\\n                self.find_packages_latests_versions(options):\n            if dist.parsed_version == remote_version_parsed:\n                uptodate.append(dist)\n        self.output_package_listing(uptodate)\n", "path": "pip/commands/list.py"}]}