Add --issue flag to git cl status.

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index 6658a2fa05aaf149ac417453e4643cf1e6a9b1f4..2df691d047548f4788c9a91d8a7e1ceb93bd2a12 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -3278,6 +3278,9 @@ def CMDstatus(parser, args):
                     help='print only specific field (desc|id|patch|status|url)')
   parser.add_option('-f', '--fast', action='store_true',
                     help='Do not retrieve review status')
+  parser.add_option('-i', '--issue', type=int,
+                    help='Operate on this issue number instead of the current'
+                      ' branch\'s implicit issue. Only valid with --field.')
   parser.add_option(
       '-j', '--maxjobs', action='store', type=int,
       help='The maximum number of jobs to use when retrieving review status')
@@ -3288,8 +3291,13 @@ def CMDstatus(parser, args):
     parser.error('Unsupported args: %s' % args)
   auth_config = auth.extract_auth_config_from_options(options)
 
+  if not options.field and options.issue is not None:

[Vadim Sh., 2016/08/17 19:39:38]

Is it None or 0? Option type is 'int', I forgot what's default value for such
options.

+    parser.error('--issue may only be specified in conjunction with --field')
+
   if options.field:
     cl = Changelist(auth_config=auth_config)

[tandrii(chromium), 2016/08/17 19:41:04]

passing it here is also OK, so long as you know which codereview is being used,
and recipe roller is still hardcoding rietveld, so how about adding
force_code_review options as say in "CMDUpload"?

+    if options.issue:
+      cl.issue = options.issue
     if options.field.startswith('desc'):
       print(cl.GetDescription())
     elif options.field == 'id':