Fixed issue #609 - method to detect VCS backend

pip/__init__.py

@@ -132,7 +132,7 @@ def from_dist(cls, dist, dependency_links, find_tags=False):
         location = os.path.normcase(os.path.abspath(dist.location))
         comments = []
         from pip.vcs import vcs, get_src_requirement
-        if vcs.get_backend_name(location):
+        if vcs.get_backend_name(dist):
             editable = True
             try:
                 req = get_src_requirement(dist, location, find_tags)

pip/vcs/__init__.py

@@ -57,12 +57,13 @@ def unregister(self, cls=None, name=None):
         else:
             logger.warn('Cannot unregister because no class or name given')
 
-    def get_backend_name(self, location):
+    def get_backend_name(self, dist):
         """
         Return the name of the version control backend if found at given
-        location, e.g. vcs.get_backend_name('/path/to/vcs/checkout')
+        location, e.g. vcs.get_backend_name(dist)
         """
         for vc_type in self._registry.values():
+            location = os.path.join(dist.location.split(dist.key)[0], dist.key)
             path = os.path.join(location, vc_type.dirname)
             if os.path.exists(path):
                 return vc_type.name
@@ -73,8 +74,8 @@ def get_backend(self, name):
         if name in self._registry:
             return self._registry[name]
 
-    def get_backend_from_location(self, location):
-        vc_type = self.get_backend_name(location)
+    def get_backend_from_location(self, dist):
+        vc_type = self.get_backend_name(dist)
         if vc_type:
             return self.get_backend(vc_type)
         return None
@@ -244,7 +245,7 @@ def get_src_requirement(self, dist, location, find_tags=False):
 
 
 def get_src_requirement(dist, location, find_tags):
-    version_control = vcs.get_backend_from_location(location)
+    version_control = vcs.get_backend_from_location(dist)
     if version_control:
         return version_control().get_src_requirement(dist, location, find_tags)
     logger.warn('cannot determine version of editable source in %s (is not SVN checkout, Git clone, Mercurial clone or Bazaar branch)' % location)