Fix TypeError: cannot concatenate 'str' and 'int' objects

BUG=None
TEST=Error log print

Review URL: https://codereview.chromium.org/112123003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@241544 0039d316-1c4b-4281-b951-d872f2087c98

git_cl.py

@@ -654,7 +654,7 @@ or verify this branch is set up to track another (via the --track argument to
                  'this command again.') % issue)
           else:
             DieWithError(
-                '\nFailed to fetch issue description. HTTP error ' + e.code)
+                '\nFailed to fetch issue description. HTTP error %d' % e.code)
       self.has_description = True
     if pretty:
       wrapper = textwrap.TextWrapper()