Stacks created in Graphite and mirrored in GitHub cannot be merged by Graphite

[pdconant-dealmaker]

It's not clear why -- Graphite just says something like "Graphite was unable to merge the PR." That makes it more challenging to explore moving, because we lose graphite's functionality just by testing GitHub.

[stepancheg]

It is because GitHub API to merge PRs (e.g. gh pr merge 234841) does not work with GH stacks. Moreover, there's no alternative API, the only way to merge stacked PRs is actually click in UI.

And on top of that, when merge queues are enabled, gh stacks cannot be merged as stacks, only one PR at a time (triggering rebase and CI again). And also there's no "merge when ready" option. That results in fulltime job of watching CI and clicking for large stacks.

It was reported before, but ignored. Like authors of gh stacks try very hard to stop people from using this feature.