Merge "Don't backtrace when current branch is not uploadable."

subcmds/upload.py

@@ -422,7 +422,16 @@ Gerrit Code Review:  http://code.google.com/p/gerrit/
     for project in project_list:
       if opt.current_branch:
         cbr = project.CurrentBranch
-        avail = [project.GetUploadableBranch(cbr)] if cbr else None
+        up_branch = project.GetUploadableBranch(cbr)
+        if up_branch:
+          avail = [up_branch]
+        else:
+          avail = None
+          print('ERROR: Current branch (%s) not uploadable. '
+                'You may be able to type '
+                '"git branch --set-upstream-to m/master" to fix '
+                'your branch.' % str(cbr),
+                file=sys.stderr)
       else:
         avail = project.GetUploadableBranches(branch)
       if avail: