Feature flags framework

[webknjaz]

I think having a quick way to enable/disable certain code paths based on a toggle and a rollout percentage is essential to having stable bot in production.
This could also facilitate restricted testing of new features.

[gundalow]

Could you please provide some examples?

[webknjaz]

if feature_enabled('new_explanation_comment', issue_id=xxxx):
  # use new experimental comment template
else:
  # use the old one

and config

new_explanation_comment: 5%

meaning that it'd use this comment for 5% of issues only. or use this just for wrapping new code. there's a lot of uses of this technique.