Shortcuts for regressions moving to the next release channel

[apiraino]

Here's a TODO for me:

Add a @rustbot to-beta shortcut for:
@rustbot label -regression-from-stable-to-nightly +regression-from-stable-to-beta

Add a @rustbot to-stable shortcut for:
@rustbot label -regression-from-stable-to-beta +regression-from-stable-to-stable

They would be very useful for me (more concise to write and no need to go to the label UI widget)

I was sure there was something like that already but I can't find them in the forge so it was probably just my imagination ...

@rustbot claim

[apiraino]

I was (almost) right, it's already in place but only for pull requests and the mapping is hardcoded
https://forge.rust-lang.org/triagebot/shortcuts.html

The handler was implemented in #1381

• Why was this handler restricted to pull requests?
• I think it could make sense reworking this handler and have it parse the configuration from the triagebot.toml