gclient: fix git version check to handle 1.6.5.2.5.g7c3ba.dirty

gclient_scm.py

Index: gclient_scm.py
diff --git a/gclient_scm.py b/gclient_scm.py
index aa5a05d33b6c60692382915553df50f92ab7e885..95a8e53813e47abeb9accf987b28c14b1dc350d1 100644
--- a/gclient_scm.py
+++ b/gclient_scm.py
@@ -188,8 +188,13 @@ class GitWrapper(SCMWrapper, scm.GIT):
       file_list.extend([os.path.join(self.checkout_path, f) for f in files])
 
   def _CheckMinVersion(self, min_version):
+    def only_int(val):
+      if val.isdigit():
+        return int(val)
+      else:
+        return 0
     version = self._Run(['--version']).split()[-1]
-    version_list = map(int, version.split('.'))
+    version_list = map(only_int, version.split('.'))
     min_version_list = map(int, min_version.split('.'))
     for min_ver in min_version_list:
       ver = version_list.pop(0)