Previous code checked the exit status of 'echo' instead of 'read' to
determine if the 'read' command had timed out.

TEST=Create a mirror of depot_tools.git, git clone it, then run
./update_depot_tools, see prompt for changing the URL, wait at
least 60 seconds and verify that you get the timeout message.

R=maruel@chromium.org
BUG=

Review URL: https://codereview.chromium.org/25110004

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@227427 0039d316-1c4b-4281-b951-d872f2087c98