Infer CL author and reviewer list from local state if the issue has not previously been uploaded.

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index 82d5a78abb6f5780fe0dafcca334cf03353e8a1a..1a1c64847f26c098dd292278249108de56e42980 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1694,6 +1694,11 @@ def CMDupload(parser, args):
     cl.SetWatchers(watchlist.GetWatchersForPaths(files))
 
   if not options.bypass_hooks:
+    if options.reviewers:
+      # Set the reviewer list now so that presubmit checks can access it.
+      change_description = ChangeDescription(change.FullDescriptionText())
+      change_description.update_reviewers(options.reviewers)
+      change.SetDescriptionText(change_description.description)
     hook_results = cl.RunHook(committing=False,
                               may_prompt=not options.force,
                               verbose=options.verbose,