Scheduled for 2.3.13.
I applied the fix and will observe it for the next couple of days.
Unfortunately, the issue still persists even with this patch. The log message is slightly different, though, regarding disconnection.
Dec 03 17:10:49 server.name kernel: indexer-worker[15805]: segfault at 0 ip 00007f140483db64 sp 00007ffc04fa7960 error 4 in libdovecot.so.0.0.0[7f14047f3000+db000]
It seems that there is something else going wrong in this version.
This is a segfault, while the fix was for an assert crash, so it's a different issue. Can you get a gdb backtrace of the crash? Otherwise we can't debug it further. See https://dovecot.org/bugreport-mail#coredumps[https://dovecot.org/bugreport-mail#coredumps]
I will try to. However, it will take some time, though, because I need to make it work in a Docker container (sysctl and read-only filesystem). I will get back to you will details as soon as possible.