Print which project _get_commits() failed for

'repo upload' may run hooks on multiple repositories.  Add error info for which project is not on a tracking branch.

BUG=None
TEST=Ran hooks with no tracking branch, and with tracking branch

Change-Id: I9c743bbac9d951045b68916236feeeddcbd31514
Reviewed-on: http://gerrit.chromium.org/gerrit/439
Tested-by: Ryan Cui <rcui@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index ed22fb2..a60e68c 100644
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -328,7 +328,13 @@
   if project in hooks:
     project_specific_hooks = hooks[project]
 
-  for commit in _get_commits():
+  try:
+    commit_list = _get_commits()
+  except:
+    print >> sys.stderr, "ERROR: project *%s*" % project
+    raise
+
+  for commit in commit_list:
     try:
       for hook in COMMON_HOOKS + project_specific_hooks:
         hook(project, commit)