Make git-cl wrapper print errors instead of silently deleting repos.

It would previously delete and recreate git-cl-repo if it
saw that the remote was different than expected.  This looks
like it was added for the transition from the old SVN repo
to the new git one, but it also has the effect of losing
any local changes that have been made in the repo. :-(

Everyone should be updated by now, so print a helpful error
and exit instead.
Review URL: http://codereview.chromium.org/609002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@39099 0039d316-1c4b-4281-b951-d872f2087c98

git-cl

@@ -1,5 +1,5 @@
 #!/bin/sh
-# Copyright (c) 2009 The Chromium Authors. All rights reserved.
+# Copyright (c) 2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
@@ -8,7 +8,19 @@ url="http://src.chromium.org/git/git-cl.git"
 cur_url=$(git config -f "$base_dir/git-cl-repo/.git/config" remote.origin.url)
 
 if [ "$cur_url" != "$url" ]; then
+  cat <<EOF
+$base_dir/git-cl-repo
+is tracking a non-default remote repository:
+
+  default: $url
+  yours:   $cur_url
+
+This is intended to be an automatically-updating, read-only repository.
+Please create a separate repository for making changes to git-cl, move your
+modifications there, and then run:
   rm -rf $base_dir/git-cl-repo
+EOF
+  exit 1
 fi
 
 if [ ! -f "$base_dir/git-cl-repo/git-cl" ]; then