[Maria-developers] Please review a fix for MDEV-10780 (and likely for MDEV-10806 and MDEV-10910)

Hello Sanja, Elena, Wlad, Sanja, please review a patch for MDEV-10780. The patch is for 10.1. I could not reproduce it in 10.0. But it should be safe to push it into 10.0 anyway. This patch is most likely fixing MDEV-10806 (assigned to Sanja) and MDEV-10910 (assigned to Elena). Thanks!