x/build/maintner/maintnerd, x/build/maintner: changes are hard to review and test

[dmitshur]

This issue is to note that it is currently difficult and time-intensive to review changes to the maintner server. Changes to the server are risky and can cause crashes, or worse, incorrect data to be written. Many services depend on the maintner server being stable and correct.

It has some tests, but they're not enough to provide sufficient confidence. Manual testing is not easy. There isn't a staging instance that's actively used.

This issue is to track progress on making it easier and safer to make changes to maintner. It has known bugs that need to be resolved, and Gerrit and GitHub APIs may change, so not making any changes will not be viable indefinitely.

/cc @cagedmantis @toothrot

[gopherbot]

Change https://golang.org/cl/216438 mentions this issue: maintner: handle deleted issues in githubRepoPoller.syncIssues