If the destination directory doesn't contain the desired repo, delete it

gclient_scm.py

Index: gclient_scm.py
diff --git a/gclient_scm.py b/gclient_scm.py
index f5a434b1edaada44cfcc93e64cf897f2d3ca5ae7..6bc9081f0f06153258a64159412582a179efd760 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -215,6 +215,13 @@ class GitWrapper(SCMWrapper):
   def GetCheckoutRoot(self):
     return scm.GIT.GetCheckoutRoot(self.checkout_path)
 
+  def GetRemoteURL(self, options, cwd=None):
+    try:
+      return self._Capture(['config', 'remote.origin.url'],
+                           cwd=cwd or self.checkout_path).rstrip()
+    except (OSError, subprocess2.CalledProcessError):
+      return None
+
   def GetRevisionDate(self, _revision):
     """Returns the given revision's date in ISO-8601 format (which contains the
     time zone)."""
@@ -375,7 +382,7 @@ class GitWrapper(SCMWrapper):
 
     # See if the url has changed (the unittests use git://foo for the url, let
     # that through).
-    current_url = self._Capture(['config', 'remote.origin.url'])
+    current_url = self.GetRemoteURL(options)
     return_early = False
     # TODO(maruel): Delete url != 'git://foo' since it's just to make the
     # unit test pass. (and update the comment above)
@@ -807,8 +814,7 @@ class GitWrapper(SCMWrapper):
         # to relax this restriction in the future to allow for smarter cache
         # repo update schemes (such as pulling the same repo, but from a
         # different host).
-        existing_url = self._Capture(['config', 'remote.origin.url'],
-                                     cwd=folder)
+        existing_url = self.GetRemoteURL(options, cwd=folder)
         assert self._NormalizeGitURL(existing_url) == self._NormalizeGitURL(url)
 
         if use_reference:
@@ -1077,6 +1083,13 @@ class SVNWrapper(SCMWrapper):
   def GetCheckoutRoot(self):
     return scm.SVN.GetCheckoutRoot(self.checkout_path)
 
+  def GetRemoteURL(self, options):
+    try:
+      local_info = scm.SVN.CaptureLocalInfo([os.curdir], self.checkout_path)
+    except (OSError, subprocess2.CalledProcessError):
+      return None
+    return local_info.get('URL')
+
   def GetRevisionDate(self, revision):
     """Returns the given revision's date in ISO-8601 format (which contains the
     time zone)."""