bug#72165: More info

[Dima Kogan]

I looked at the backtrace a bit. Here's the failing assert:

  
https://github.com/dkogan/emacs-snapshot/blob/439ec471961b764b51483b74ea13777ed560fd74/src/xdisp.c#L20086

This is false:

  Z == Z_BYTE && CHARPOS (opoint) != BYTEPOS (opoint)

The backtrace is silent about the specific values of each of these, but
I can try to get them. Debugging suggestions welcome.