prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  When --dashboard-prefix is used root location is always redirected to /status without adding the prefix
  The problem arises when using --dashboard-prefix, using http://DASHBOARD[:PORT]/PREFIX/ redirects to http://DASHBOARD[:PORT]/status instead of http://DASHBOARD[:PORT]/PREFIX/status.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `distributed/dashboard/core.py`
  Content:
  ```
  1 from distutils.version import LooseVersion
  2 import os
  3 import warnings
  4 
  5 import bokeh
  6 from bokeh.server.server import Server
  7 from tornado import web
  8 
  9 
  10 if LooseVersion(bokeh.__version__) < LooseVersion("0.13.0"):
  11     warnings.warn(
  12         "\nDask needs bokeh >= 0.13.0 for the dashboard."
  13         "\nContinuing without the dashboard."
  14     )
  15     raise ImportError("Dask needs bokeh >= 0.13.0")
  16 
  17 
  18 class BokehServer(object):
  19     server_kwargs = {}
  20 
  21     def listen(self, addr):
  22         if self.server:
  23             return
  24         if isinstance(addr, tuple):
  25             ip, port = addr
  26         else:
  27             port = addr
  28             ip = None
  29         for i in range(5):
  30             try:
  31                 server_kwargs = dict(
  32                     port=port,
  33                     address=ip,
  34                     check_unused_sessions_milliseconds=500,
  35                     allow_websocket_origin=["*"],
  36                     use_index=False,
  37                     extra_patterns=[(r"/", web.RedirectHandler, {"url": "/status"})],
  38                 )
  39                 server_kwargs.update(self.server_kwargs)
  40                 self.server = Server(self.apps, **server_kwargs)
  41                 self.server.start()
  42 
  43                 handlers = [
  44                     (
  45                         self.prefix + r"/statics/(.*)",
  46                         web.StaticFileHandler,
  47                         {"path": os.path.join(os.path.dirname(__file__), "static")},
  48                     )
  49                 ]
  50 
  51                 self.server._tornado.add_handlers(r".*", handlers)
  52 
  53                 return
  54             except (SystemExit, EnvironmentError) as exc:
  55                 if port != 0:
  56                     if "already in use" in str(
  57                         exc
  58                     ) or "Only one usage of" in str(  # Unix/Mac
  59                         exc
  60                     ):  # Windows
  61                         msg = (
  62                             "Port %d is already in use. "
  63                             "\nPerhaps you already have a cluster running?"
  64                             "\nHosting the diagnostics dashboard on a random port instead."
  65                             % port
  66                         )
  67                     else:
  68                         msg = (
  69                             "Failed to start diagnostics server on port %d. " % port
  70                             + str(exc)
  71                         )
  72                     warnings.warn("\n" + msg)
  73                     port = 0
  74                 if i == 4:
  75                     raise
  76 
  77     @property
  78     def port(self):
  79         return (
  80             self.server.port
  81             or list(self.server._http._sockets.values())[0].getsockname()[1]
  82         )
  83 
  84     def stop(self):
  85         for context in self.server._tornado._applications.values():
  86             context.run_unload_hook()
  87 
  88         self.server._tornado._stats_job.stop()
  89         self.server._tornado._cleanup_job.stop()
  90         if self.server._tornado._ping_job is not None:
  91             self.server._tornado._ping_job.stop()
  92 
  93         # https://github.com/bokeh/bokeh/issues/5494
  94         if LooseVersion(bokeh.__version__) >= "0.12.4":
  95             self.server.stop()
  96
  ```
  --- 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()
  
  ```
  
golden_diff: diff --git a/distributed/dashboard/core.py b/distributed/dashboard/core.py
  --- a/distributed/dashboard/core.py
  +++ b/distributed/dashboard/core.py
  @@ -5,6 +5,7 @@
   import bokeh
   from bokeh.server.server import Server
   from tornado import web
  +from urllib.parse import urljoin
   
   
   if LooseVersion(bokeh.__version__) < LooseVersion("0.13.0"):
  @@ -34,7 +35,13 @@
                       check_unused_sessions_milliseconds=500,
                       allow_websocket_origin=["*"],
                       use_index=False,
  -                    extra_patterns=[(r"/", web.RedirectHandler, {"url": "/status"})],
  +                    extra_patterns=[
  +                        (
  +                            r"/",
  +                            web.RedirectHandler,
  +                            {"url": urljoin(self.prefix.rstrip("/") + "/", r"status")},
  +                        )
  +                    ],
                   )
                   server_kwargs.update(self.server_kwargs)
                   self.server = Server(self.apps, **server_kwargs)
  
verification_info: {"golden_diff": "diff --git a/distributed/dashboard/core.py b/distributed/dashboard/core.py\n--- a/distributed/dashboard/core.py\n+++ b/distributed/dashboard/core.py\n@@ -5,6 +5,7 @@\n import bokeh\n from bokeh.server.server import Server\n from tornado import web\n+from urllib.parse import urljoin\n \n \n if LooseVersion(bokeh.__version__) < LooseVersion(\"0.13.0\"):\n@@ -34,7 +35,13 @@\n                     check_unused_sessions_milliseconds=500,\n                     allow_websocket_origin=[\"*\"],\n                     use_index=False,\n-                    extra_patterns=[(r\"/\", web.RedirectHandler, {\"url\": \"/status\"})],\n+                    extra_patterns=[\n+                        (\n+                            r\"/\",\n+                            web.RedirectHandler,\n+                            {\"url\": urljoin(self.prefix.rstrip(\"/\") + \"/\", r\"status\")},\n+                        )\n+                    ],\n                 )\n                 server_kwargs.update(self.server_kwargs)\n                 self.server = Server(self.apps, **server_kwargs)\n", "issue": "When --dashboard-prefix is used root location is always redirected to /status without adding the prefix\nThe problem arises when using --dashboard-prefix, using http://DASHBOARD[:PORT]/PREFIX/ redirects to http://DASHBOARD[:PORT]/status instead of http://DASHBOARD[:PORT]/PREFIX/status.\n", "before_files": [{"content": "from distutils.version import LooseVersion\nimport os\nimport warnings\n\nimport bokeh\nfrom bokeh.server.server import Server\nfrom tornado import web\n\n\nif LooseVersion(bokeh.__version__) < LooseVersion(\"0.13.0\"):\n    warnings.warn(\n        \"\\nDask needs bokeh >= 0.13.0 for the dashboard.\"\n        \"\\nContinuing without the dashboard.\"\n    )\n    raise ImportError(\"Dask needs bokeh >= 0.13.0\")\n\n\nclass BokehServer(object):\n    server_kwargs = {}\n\n    def listen(self, addr):\n        if self.server:\n            return\n        if isinstance(addr, tuple):\n            ip, port = addr\n        else:\n            port = addr\n            ip = None\n        for i in range(5):\n            try:\n                server_kwargs = dict(\n                    port=port,\n                    address=ip,\n                    check_unused_sessions_milliseconds=500,\n                    allow_websocket_origin=[\"*\"],\n                    use_index=False,\n                    extra_patterns=[(r\"/\", web.RedirectHandler, {\"url\": \"/status\"})],\n                )\n                server_kwargs.update(self.server_kwargs)\n                self.server = Server(self.apps, **server_kwargs)\n                self.server.start()\n\n                handlers = [\n                    (\n                        self.prefix + r\"/statics/(.*)\",\n                        web.StaticFileHandler,\n                        {\"path\": os.path.join(os.path.dirname(__file__), \"static\")},\n                    )\n                ]\n\n                self.server._tornado.add_handlers(r\".*\", handlers)\n\n                return\n            except (SystemExit, EnvironmentError) as exc:\n                if port != 0:\n                    if \"already in use\" in str(\n                        exc\n                    ) or \"Only one usage of\" in str(  # Unix/Mac\n                        exc\n                    ):  # Windows\n                        msg = (\n                            \"Port %d is already in use. \"\n                            \"\\nPerhaps you already have a cluster running?\"\n                            \"\\nHosting the diagnostics dashboard on a random port instead.\"\n                            % port\n                        )\n                    else:\n                        msg = (\n                            \"Failed to start diagnostics server on port %d. \" % port\n                            + str(exc)\n                        )\n                    warnings.warn(\"\\n\" + msg)\n                    port = 0\n                if i == 4:\n                    raise\n\n    @property\n    def port(self):\n        return (\n            self.server.port\n            or list(self.server._http._sockets.values())[0].getsockname()[1]\n        )\n\n    def stop(self):\n        for context in self.server._tornado._applications.values():\n            context.run_unload_hook()\n\n        self.server._tornado._stats_job.stop()\n        self.server._tornado._cleanup_job.stop()\n        if self.server._tornado._ping_job is not None:\n            self.server._tornado._ping_job.stop()\n\n        # https://github.com/bokeh/bokeh/issues/5494\n        if LooseVersion(bokeh.__version__) >= \"0.12.4\":\n            self.server.stop()\n", "path": "distributed/dashboard/core.py"}], "after_files": [{"content": "from distutils.version import LooseVersion\nimport os\nimport warnings\n\nimport bokeh\nfrom bokeh.server.server import Server\nfrom tornado import web\nfrom urllib.parse import urljoin\n\n\nif LooseVersion(bokeh.__version__) < LooseVersion(\"0.13.0\"):\n    warnings.warn(\n        \"\\nDask needs bokeh >= 0.13.0 for the dashboard.\"\n        \"\\nContinuing without the dashboard.\"\n    )\n    raise ImportError(\"Dask needs bokeh >= 0.13.0\")\n\n\nclass BokehServer(object):\n    server_kwargs = {}\n\n    def listen(self, addr):\n        if self.server:\n            return\n        if isinstance(addr, tuple):\n            ip, port = addr\n        else:\n            port = addr\n            ip = None\n        for i in range(5):\n            try:\n                server_kwargs = dict(\n                    port=port,\n                    address=ip,\n                    check_unused_sessions_milliseconds=500,\n                    allow_websocket_origin=[\"*\"],\n                    use_index=False,\n                    extra_patterns=[\n                        (\n                            r\"/\",\n                            web.RedirectHandler,\n                            {\"url\": urljoin(self.prefix.rstrip(\"/\") + \"/\", r\"status\")},\n                        )\n                    ],\n                )\n                server_kwargs.update(self.server_kwargs)\n                self.server = Server(self.apps, **server_kwargs)\n                self.server.start()\n\n                handlers = [\n                    (\n                        self.prefix + r\"/statics/(.*)\",\n                        web.StaticFileHandler,\n                        {\"path\": os.path.join(os.path.dirname(__file__), \"static\")},\n                    )\n                ]\n\n                self.server._tornado.add_handlers(r\".*\", handlers)\n\n                return\n            except (SystemExit, EnvironmentError) as exc:\n                if port != 0:\n                    if \"already in use\" in str(\n                        exc\n                    ) or \"Only one usage of\" in str(  # Unix/Mac\n                        exc\n                    ):  # Windows\n                        msg = (\n                            \"Port %d is already in use. \"\n                            \"\\nPerhaps you already have a cluster running?\"\n                            \"\\nHosting the diagnostics dashboard on a random port instead.\"\n                            % port\n                        )\n                    else:\n                        msg = (\n                            \"Failed to start diagnostics server on port %d. \" % port\n                            + str(exc)\n                        )\n                    warnings.warn(\"\\n\" + msg)\n                    port = 0\n                if i == 4:\n                    raise\n\n    @property\n    def port(self):\n        return (\n            self.server.port\n            or list(self.server._http._sockets.values())[0].getsockname()[1]\n        )\n\n    def stop(self):\n        for context in self.server._tornado._applications.values():\n            context.run_unload_hook()\n\n        self.server._tornado._stats_job.stop()\n        self.server._tornado._cleanup_job.stop()\n        if self.server._tornado._ping_job is not None:\n            self.server._tornado._ping_job.stop()\n\n        # https://github.com/bokeh/bokeh/issues/5494\n        if LooseVersion(bokeh.__version__) >= \"0.12.4\":\n            self.server.stop()\n", "path": "distributed/dashboard/core.py"}]}