prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Bug: dvc remote remove leads to Initialization error / config file error.
  **Setup**
  
  - dvc version 0.18.9, installed with pip, python Anaconda 3.6.4, Ubuntu 16.04
  
  **Repro**
  
  ```bash
  set -e
  set -x
  rm -rf foo
  mkdir -p foo && cd foo
  git init && dvc init
  echo bar > bar.txt
  dvc remote add -d dummy s3://dummy
  dvc remote remove dummy
  dvc add bar.txt
  ```
  
  ```bash
  + rm -rf foo
  + mkdir -p foo
  + cd foo
  + git init
  Initialized empty Git repository in /home/tmain/foo/.git/
  + dvc init
  Adding '.dvc/state' to '.dvc/.gitignore'.
  Adding '.dvc/state.lock' to '.dvc/.gitignore'.
  Adding '.dvc/link.state' to '.dvc/.gitignore'.
  Adding '.dvc/link.state.lock' to '.dvc/.gitignore'.
  Adding '.dvc/lock' to '.dvc/.gitignore'.
  Adding '.dvc/config.local' to '.dvc/.gitignore'.
  Adding '.dvc/updater' to '.dvc/.gitignore'.
  Adding '.dvc/cache' to '.dvc/.gitignore'.
  Checking for updates...
  + echo bar
  + dvc remote add -d dummy s3://dummy
  Setting 'dummy' as a default remote.
  + dvc remote remove dummy
  + dvc add bar.txt
  Error: Initialization error: Config file error: Can't find remote section 'remote "dummy"' in config
  
  ```
  
  </issue>
  <code>
  [start of dvc/command/remote.py]
  1 import re
  2 
  3 from dvc.config import Config
  4 from dvc.command.config import CmdConfig
  5 from dvc.logger import Logger
  6 
  7 
  8 class CmdRemoteAdd(CmdConfig):
  9     def run(self):
  10         section = Config.SECTION_REMOTE_FMT.format(self.args.name)
  11         ret = self.set(section, Config.SECTION_REMOTE_URL, self.args.url)
  12         if ret != 0:
  13             return ret
  14 
  15         if self.args.default:
  16             msg = 'Setting \'{}\' as a default remote.'.format(self.args.name)
  17             Logger.info(msg)
  18             ret = self.set(Config.SECTION_CORE,
  19                            Config.SECTION_CORE_REMOTE,
  20                            self.args.name)
  21 
  22         return ret
  23 
  24 
  25 class CmdRemoteRemove(CmdConfig):
  26     def run(self):
  27         section = Config.SECTION_REMOTE_FMT.format(self.args.name)
  28         return self.unset(section, Config.SECTION_REMOTE_URL)
  29 
  30 
  31 class CmdRemoteModify(CmdConfig):
  32     def run(self):
  33         section = Config.SECTION_REMOTE_FMT.format(self.args.name)
  34         self.args.name = '{}.{}'.format(section, self.args.option)
  35         return super(CmdRemoteModify, self).run()
  36 
  37 
  38 class CmdRemoteList(CmdConfig):
  39     def run(self):
  40         for section in self.configobj.keys():
  41             r = re.match(Config.SECTION_REMOTE_REGEX, section)
  42             if r:
  43                 name = r.group('name')
  44                 url = self.configobj[section].get(Config.SECTION_REMOTE_URL,
  45                                                   '')
  46                 Logger.info('{}\t{}'.format(name, url))
  47         return 0
  48
  [end of dvc/command/remote.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/dvc/command/remote.py b/dvc/command/remote.py
  --- a/dvc/command/remote.py
  +++ b/dvc/command/remote.py
  @@ -1,4 +1,6 @@
  +import os
   import re
  +import configobj
   
   from dvc.config import Config
   from dvc.command.config import CmdConfig
  @@ -23,9 +25,35 @@
   
   
   class CmdRemoteRemove(CmdConfig):
  +    def _remove_default(self, config_file, remote):
  +        path = os.path.join(os.path.dirname(self.config_file),
  +                            config_file)
  +        config = configobj.ConfigObj(path)
  +
  +        core = config.get(Config.SECTION_CORE, None)
  +        if core is None:
  +            return
  +
  +        default = core.get(Config.SECTION_CORE_REMOTE, None)
  +        if default is None:
  +            return
  +
  +        if default == remote:
  +            del config[Config.SECTION_CORE][Config.SECTION_CORE_REMOTE]
  +            if len(config[Config.SECTION_CORE]) == 0:
  +                del config[Config.SECTION_CORE]
  +
  +        config.write()
  +
       def run(self):
           section = Config.SECTION_REMOTE_FMT.format(self.args.name)
  -        return self.unset(section, Config.SECTION_REMOTE_URL)
  +        ret = self.unset(section)
  +        if ret != 0:
  +            return ret
  +
  +        self._remove_default(Config.CONFIG, self.args.name)
  +        self._remove_default(Config.CONFIG_LOCAL, self.args.name)
  +        return 0
   
   
   class CmdRemoteModify(CmdConfig):
  
verification_info: {"golden_diff": "diff --git a/dvc/command/remote.py b/dvc/command/remote.py\n--- a/dvc/command/remote.py\n+++ b/dvc/command/remote.py\n@@ -1,4 +1,6 @@\n+import os\n import re\n+import configobj\n \n from dvc.config import Config\n from dvc.command.config import CmdConfig\n@@ -23,9 +25,35 @@\n \n \n class CmdRemoteRemove(CmdConfig):\n+    def _remove_default(self, config_file, remote):\n+        path = os.path.join(os.path.dirname(self.config_file),\n+                            config_file)\n+        config = configobj.ConfigObj(path)\n+\n+        core = config.get(Config.SECTION_CORE, None)\n+        if core is None:\n+            return\n+\n+        default = core.get(Config.SECTION_CORE_REMOTE, None)\n+        if default is None:\n+            return\n+\n+        if default == remote:\n+            del config[Config.SECTION_CORE][Config.SECTION_CORE_REMOTE]\n+            if len(config[Config.SECTION_CORE]) == 0:\n+                del config[Config.SECTION_CORE]\n+\n+        config.write()\n+\n     def run(self):\n         section = Config.SECTION_REMOTE_FMT.format(self.args.name)\n-        return self.unset(section, Config.SECTION_REMOTE_URL)\n+        ret = self.unset(section)\n+        if ret != 0:\n+            return ret\n+\n+        self._remove_default(Config.CONFIG, self.args.name)\n+        self._remove_default(Config.CONFIG_LOCAL, self.args.name)\n+        return 0\n \n \n class CmdRemoteModify(CmdConfig):\n", "issue": "Bug: dvc remote remove leads to Initialization error / config file error.\n**Setup**\r\n\r\n- dvc version 0.18.9, installed with pip, python Anaconda 3.6.4, Ubuntu 16.04\r\n\r\n**Repro**\r\n\r\n```bash\r\nset -e\r\nset -x\r\nrm -rf foo\r\nmkdir -p foo && cd foo\r\ngit init && dvc init\r\necho bar > bar.txt\r\ndvc remote add -d dummy s3://dummy\r\ndvc remote remove dummy\r\ndvc add bar.txt\r\n```\r\n\r\n```bash\r\n+ rm -rf foo\r\n+ mkdir -p foo\r\n+ cd foo\r\n+ git init\r\nInitialized empty Git repository in /home/tmain/foo/.git/\r\n+ dvc init\r\nAdding '.dvc/state' to '.dvc/.gitignore'.\r\nAdding '.dvc/state.lock' to '.dvc/.gitignore'.\r\nAdding '.dvc/link.state' to '.dvc/.gitignore'.\r\nAdding '.dvc/link.state.lock' to '.dvc/.gitignore'.\r\nAdding '.dvc/lock' to '.dvc/.gitignore'.\r\nAdding '.dvc/config.local' to '.dvc/.gitignore'.\r\nAdding '.dvc/updater' to '.dvc/.gitignore'.\r\nAdding '.dvc/cache' to '.dvc/.gitignore'.\r\nChecking for updates...\r\n+ echo bar\r\n+ dvc remote add -d dummy s3://dummy\r\nSetting 'dummy' as a default remote.\r\n+ dvc remote remove dummy\r\n+ dvc add bar.txt\r\nError: Initialization error: Config file error: Can't find remote section 'remote \"dummy\"' in config\r\n\r\n```\n", "before_files": [{"content": "import re\n\nfrom dvc.config import Config\nfrom dvc.command.config import CmdConfig\nfrom dvc.logger import Logger\n\n\nclass CmdRemoteAdd(CmdConfig):\n    def run(self):\n        section = Config.SECTION_REMOTE_FMT.format(self.args.name)\n        ret = self.set(section, Config.SECTION_REMOTE_URL, self.args.url)\n        if ret != 0:\n            return ret\n\n        if self.args.default:\n            msg = 'Setting \\'{}\\' as a default remote.'.format(self.args.name)\n            Logger.info(msg)\n            ret = self.set(Config.SECTION_CORE,\n                           Config.SECTION_CORE_REMOTE,\n                           self.args.name)\n\n        return ret\n\n\nclass CmdRemoteRemove(CmdConfig):\n    def run(self):\n        section = Config.SECTION_REMOTE_FMT.format(self.args.name)\n        return self.unset(section, Config.SECTION_REMOTE_URL)\n\n\nclass CmdRemoteModify(CmdConfig):\n    def run(self):\n        section = Config.SECTION_REMOTE_FMT.format(self.args.name)\n        self.args.name = '{}.{}'.format(section, self.args.option)\n        return super(CmdRemoteModify, self).run()\n\n\nclass CmdRemoteList(CmdConfig):\n    def run(self):\n        for section in self.configobj.keys():\n            r = re.match(Config.SECTION_REMOTE_REGEX, section)\n            if r:\n                name = r.group('name')\n                url = self.configobj[section].get(Config.SECTION_REMOTE_URL,\n                                                  '')\n                Logger.info('{}\\t{}'.format(name, url))\n        return 0\n", "path": "dvc/command/remote.py"}]}