Reverting VersionControl.controls_location() to pre PR state. Its a…

…n optimization that belongs in another PR.

src/pip/_internal/vcs/versioncontrol.py

@@ -656,17 +656,10 @@ def controls_location(cls, location):
         # type: (str) -> bool
         """
         Check if a location is controlled by the vcs.
+        It is meant to be overridden to implement smarter detection
+        mechanisms for specific vcs.
 
-        Searches up the filesystem and checks is_repository_directory().
-
-        It is meant to be extended to add smarter detection mechanisms for
-        specific vcs.  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.
         """
-        while not cls.is_repository_directory(location):
-            last_location = location
-            location = os.path.dirname(location)
-            if location == last_location:
-                # We've traversed up to the root of the filesystem.
-                return False
-        return True
+        return cls.is_repository_directory(location)