Extract list of people allowed to review from MAINTAINERS

[hauleth]

There is nice https://lgtm.co/ project that provide quite similar functionality but instead of configuration file it uses MAINTAINERS file inside repository. It would be nice addition to Homu.

[barosl]

Interesting. Is the MAINTAINERS format widely accepted?

[hauleth]

I think it is quite popular and it could be just an addition as a fallback if there is no configuration file.

[barosl]

Actually, it is already possible to look up the GitHub collaborator list using the GitHub API. The reasons Homu didn't do that were:

1. You may want to give a user the r+ permission, but not a direct access to the repository. In that case you can only add the user as a reviewer, but not as a GitHub collaborator.
2. It consumes one additional GitHub API request, which counts against the rate limit.

Being able to modify MAINTAINERS means being able to add arbitrary reviewers. In the current approach, only GitHub collaborators can add new reviewers, so they can be thought as admins. However, the suggested method will grant that permission to any reviewers. I guess this is OK in general, but I'm curious if the previous workflow may be useful to some people.

[ashcrow]

For the heck of it I threw together https://github.com/ashcrow/maintainers which could be helpful here.

"Python3 library for parsing MAINTAINERS files. It can parse the non toml formats listed at lgtm."