Another attempt: gclient: delete mismatching checkouts

scm.py

Index: scm.py
diff --git a/scm.py b/scm.py
index 30bb3d17ea49bd74c0a83af490bbc486d60e3f41..7d324f8ae08752a12be329e0a7ef9e293c2371e3 100644
--- a/scm.py
+++ b/scm.py
@@ -166,8 +166,21 @@ class GIT(object):
     return GIT.ShortBranchName(GIT.GetBranchRef(cwd))
 
   @staticmethod
+  def IsGit(cwd):
+    """Returns True if this repo looks like it's using git."""
+    if os.path.exists(os.path.join(cwd, '.git')):
+      return True
+    if os.path.isdir(os.path.join(cwd, '.svn')):
+      return False
+    try:
+      GIT.Capture(['config', '--local', '--list'], cwd=cwd)
+      return True
+    except subprocess2.CalledProcessError:
+      return False
+
+  @staticmethod
   def IsGitSvn(cwd):
-    """Returns true if this repo looks like it's using git-svn."""
+    """Returns True if this repo looks like it's using git-svn."""
     # If you have any "svn-remote.*" config keys, we think you're using svn.
     try:
       GIT.Capture(['config', '--local', '--get-regexp', r'^svn-remote\.'],