Support msysgit with Chromium.

update_depot_tools

 #!/usr/bin/env bash
 # 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.
 
 # This script will try to sync the bootstrap directories and then defer control.
 
 base_dir=$(dirname "$0")
 
 # Test git and git --version.
@@ skipping 28 matching lines @@
 }
 
 
 # Update git checkouts prior the cygwin check, we don't want to use msysgit.
 if [ "X$DEPOT_TOOLS_UPDATE" != "X0" -a -e "$base_dir/.git" ]
 then
   cd $base_dir
   test_git_svn
   # work around a git-svn --quiet bug
   OUTPUT=`git svn rebase -q -q`
-  if [[ ! "$OUTPUT" =~ Current.branch ]]; then
+  if [[ ! "$OUTPUT" == *Current.branch* ]]; then
     echo $OUTPUT
   fi
   cd - > /dev/null
 fi
 
 # We're on POSIX. We can now safely look for svn checkout.
 if [ "X$DEPOT_TOOLS_UPDATE" != "X0" -a -e "$base_dir/.svn" ]
 then
   # Update the bootstrap directory to stay up-to-date with the latest
   # depot_tools.
   svn -q up "$base_dir"
 fi