Disable colors if not a tty.

Otherwise this breaks git cl unit tests.

Update references to 'git cl' in git cl smoke tests to $GIT_CL.

TBR=ilevy@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/20888002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@214019 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/git_cl.py b/git_cl.py
index 1dcb1fe..0ac0f86 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1169,8 +1169,12 @@
       b, i, color = output.get()
       tmp[b] = (i, color)
     issue, color = tmp.pop(branch)
+    reset = Fore.RESET
+    if not sys.stdout.isatty():
+      color = ''
+      reset = ''
     print '  %*s: %s%s%s' % (
-          alignment, ShortBranchName(branch), color, issue, Fore.RESET)
+          alignment, ShortBranchName(branch), color, issue, reset)
 
   cl = Changelist()
   print