4700: Add a flag (or modify existing flag) to rbt post to override OPEN_BROWSER setting from config files


What version are you running?


Describe the enhancement and the motivation for it.

Adding a flag to allow users to explicitly disable the open browser default from the .reviewboardrc file under a repository (such as rbt post --no-browser). The motivation is to offer users the capability of overriding configs like OPEN_BROWSER which potentially breaks the user experience of their development tooling if they were working with a repository that contains a .reviewboardrc file. Perhaps adding overrides can also apply to other rbt arguments.

Please provide any additional information below.