Detect all registered VCS and choose inner-most

src/pip/_internal/vcs/git.py

@@ -11,7 +11,7 @@
 from pip._vendor.six.moves.urllib import parse as urllib_parse
 from pip._vendor.six.moves.urllib import request as urllib_request
 
-from pip._internal.exceptions import BadCommand
+from pip._internal.exceptions import BadCommand, InstallationError
 from pip._internal.utils.misc import display_path, hide_url
 from pip._internal.utils.subprocess import make_command
 from pip._internal.utils.temp_dir import TempDirectory
@@ -370,20 +370,23 @@ def update_submodules(cls, location):
         )
 
     @classmethod
-    def controls_location(cls, location):
-        if super(Git, cls).controls_location(location):
-            return True
+    def get_repository_root(cls, location):
+        loc = super(Git, cls).get_repository_root(location)
+        if loc:
+            return loc
         try:
-            r = cls.run_command(['rev-parse'],
+            r = cls.run_command(['rev-parse', '--show-toplevel'],
                                 cwd=location,
                                 show_stdout=False,
-                                on_returncode='ignore',
+                                on_returncode='raise',
                                 log_failed_cmd=False)
-            return not r
         except BadCommand:
             logger.debug("could not determine if %s is under git control "
                          "because git is not available", location)
-            return False
+            return None
+        except InstallationError:
+            return None
+        return r
 
 
 vcs.register(Git)

src/pip/_internal/vcs/mercurial.py

@@ -137,19 +137,20 @@ def get_subdirectory(cls, location):
         return find_path_to_setup_from_repo_root(location, repo_root)
 
     @classmethod
-    def controls_location(cls, location):
-        if super(Mercurial, cls).controls_location(location):
-            return True
+    def get_repository_root(cls, location):
+        loc = super(Mercurial, cls).get_repository_root(location)
+        if loc:
+            return loc
         try:
-            cls.run_command(
-                ['identify'],
+            r = cls.run_command(
+                ['root'],
                 cwd=location,
                 show_stdout=False,
                 on_returncode='raise',
                 log_failed_cmd=False)
-            return True
         except (BadCommand, InstallationError):
-            return False
+            return None
+        return r
 
 
 vcs.register(Mercurial)

src/pip/_internal/vcs/versioncontrol.py

@@ -232,12 +232,20 @@ def get_backend_for_dir(self, location):
         Return a VersionControl object if a repository of that type is found
         at the given directory.
         """
+        candidates = {}
         for vcs_backend in self._registry.values():
-            if vcs_backend.controls_location(location):
-                logger.debug('Determine that %s uses VCS: %s',
-                             location, vcs_backend.name)
-                return vcs_backend
-        return None
+            root = vcs_backend.get_repository_root(location)
+            if not root:
+                continue
+            logger.debug('Determine that %s uses VCS: %s',
+                         location, vcs_backend.name)
+            candidates[root] = vcs_backend
+
+        # Choose the VCS in the inner-most directory (i.e. path to root
+        # is longest).
+        if not candidates:
+            return None
+        return candidates[max(candidates, key=len)]
 
     def get_backend_for_scheme(self, scheme):
         # type: (str) -> Optional[VersionControl]
@@ -687,14 +695,18 @@ def is_repository_directory(cls, path):
         return os.path.exists(os.path.join(path, cls.dirname))
 
     @classmethod
-    def controls_location(cls, location):
-        # type: (str) -> bool
+    def get_repository_root(cls, location):
+        # type: (str) -> Optional[str]
         """
-        Check if a location is controlled by the vcs.
+        Return the "root" (top-level) directory controlled by the vcs,
+        or ``None`` if the directory is not in any.
+
         It is meant to be overridden to implement smarter detection
         mechanisms for specific vcs.
 
-        This can do more than is_repository_directory() alone.  For example,
-        the Git override checks that Git is actually available.
+        This can do more than is_repository_directory() alone. For
+        example, the Git override checks that Git is actually available.
         """
-        return cls.is_repository_directory(location)
+        if cls.is_repository_directory(location):
+            return location
+        return None