Comment 2 for bug 74031

it already shows data about failed mirroring attempts when the last attempt was a failure.

I think a reasonable UI would be:
for non-hosted branches:
 'next mirror: 7 hours away' and
 'last mirrored: 17 hours ago'

and given that hosted branches have better granularity, and for consistency, it might be nice on hosted branches to show:
 'next mirror: automatic on push' and
 'last mirrored: 23 days ago'