https://gitlab.freedesktop.org/mesa/mesa/commit/30a01cd9232ed83a0259d184b82e050bae219ed3 has to be re-worked to work/to be integrated into with the software renderer as well.
Forget to add https://gitlab.freedesktop.org/mesa/mesa/merge_requests/818 as related.
Apologies, the commit that fixes the problem is actually 903ad59407ac965f9fbc8c0c397cc6f09263a2b8: not the one that I posted initially (it fixes that actually).
Giving this a quick stab, is this what you mean?
This seems to happen only when resizing the window before having a change to flip the back/current buffers. Pushed I fix which works but not sure if fixes the problem at the correct level:
-- GitLab Migration Automatic Message --
This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.
You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/mesa/mesa/issues/328.