Re-reland r245404 ("If the destination directory doesn't contain the desired repo, delete it")

scm.py

Index: scm.py
diff --git a/scm.py b/scm.py
index 30bb3d17ea49bd74c0a83af490bbc486d60e3f41..e0f17004c9945289b138fc649cd300df0bab2090 100644
--- a/scm.py
+++ b/scm.py
@@ -166,12 +166,15 @@ class GIT(object):
     return GIT.ShortBranchName(GIT.GetBranchRef(cwd))
 
   @staticmethod
-  def IsGitSvn(cwd):
+  def IsGitSvn(checkout_root):
     """Returns true if this repo looks like it's using git-svn."""
+    # A git-svn checkout has a .git directory.
+    if not os.path.isdir(os.path.join(checkout_root, '.git')):
+      return False

[borenet, 2014/02/06 16:21:47]

From what I can tell, the last version was failing to update pure-svn DEPS from
a git-svn checkout.  It was skipping them, because this function was giving
false positives.  The cause is that "git config" will search parent directories
until it finds a .git directory, thus tricking gclient into thinking that all of
the svn DEPS are part of the same git-svn checkout.  Therefore, we enforce that
this function must run in the checkout root where the .git directory would be.

[iannucci, 2014/02/06 23:05:11]

Yeah that makes sense... gclient supports too many combinations :/

     # If you have any "svn-remote.*" config keys, we think you're using svn.
     try:
       GIT.Capture(['config', '--local', '--get-regexp', r'^svn-remote\.'],
-                  cwd=cwd)
+                  cwd=checkout_root)
       return True
     except subprocess2.CalledProcessError:
       return False
@@ -313,7 +316,7 @@ class GIT(object):
           pass
       else:
         # Fall back on trying a git-svn upstream branch.
-        if GIT.IsGitSvn(cwd):
+        if GIT.IsGitSvn(checkout_root=cwd):
           upstream_branch = GIT.GetSVNBranch(cwd)
         else:
           # Else, try to guess the origin remote.
@@ -408,7 +411,7 @@ class GIT(object):
   @staticmethod
   def GetSha1ForSvnRev(cwd, rev):
     """Returns a corresponding git sha1 for a SVN revision."""
-    if not GIT.IsGitSvn(cwd=cwd):
+    if not GIT.IsGitSvn(checkout_root=cwd):
       return None
     try:
       output = GIT.Capture(['svn', 'find-rev', 'r' + str(rev)], cwd=cwd)