[Upgrade] pagure: 2.90.1

[Pierre-Yves Chibon]

Good Morning Everyone,

Shortly after releasing 2.15 we realized the SQL-based locking mechanism we had
introduced was causing more problems than solving.
So we released 2.15.1 to try to mitigate them but that wasn't satisfactory.

Patrick has spent the majority of his time since the end of the last week (and
thus a good part of his week-end) re-architecturing how pagure writes to git
repos so that it is now handled by an async service (running under the service
pagure_worker).
The change is so large that it was deemed worthy of being called pagure 3.0.

However, we needed to stabilize the pagure instance running on pagure.io, among
other because it is being used by releng for releasing.
So, we decided to create pre-3.0 releases: 2.90.0 yesterday, then 2.90.1 today
that include the new architecture but aren't official releases (no tags, just
commits in a side-branch and their tarball uploaded).

Kevin had +1 the upgrade earlier this week on IRC. Patrick and I being both
involved in the change (Patrick to write it, me to test, merge and release)
considered we both counted as +0.5, making this the required +2.

After pushing 2.90.1 to stg and testing it there, we considered it good to go
and pushed it to prod.

So pagure should be much more stable and able to cope with the coming days, and
we'll cut the official 3.0 after freeze once all docs have been adjusted.


Thanks to Patrick for leading this change!


Happy hacking!

Pierre