Fix mirror bug (#33597)

[GiteaBot]

Backport #33597 by @ericLemanissier

follows-up be4e961

This is the same modification as be4e961 but for force-pushes.
It is needed, because git fetch reveals force pushes for github mirrors:

$ git fetch --tags origin
remote: Enumerating objects: 22, done.
remote: Counting objects: 100% (22/22), done.
remote: Compressing objects: 100% (4/4), done.
remote: Total 9 (delta 5), reused 8 (delta 5), pack-reused 0 (from 0)
Unpacking objects: 100% (9/9), 1.70 KiB | 12.00 KiB/s, done.
From https://github.com/conan-io/conan-center-index
   729f0f1b8f..48184eddeb  refs/pull/26595/head  -> refs/pull/26595/head
 + 0c31ab60a3...1283cca9e7 refs/pull/26595/merge -> refs/pull/26595/merge  (forced update)

Fix #33200

PS: I did not test the modification, but it is the exact same change as the last hunk in https://github.com/go-gitea/gitea/pull/33224/files#diff-bb5cdb90db0f0e7f6716c0e6d0b9cbb67f08d82052b03ab3a7b5e23a1d76aed7 , just moved to the previous case of the switch

I think it could and should be back-ported to 1.23