flaky regression(?) - patch.py?id=1012510895681951425038278

Good day!

Something in this patch makes my app set This->bigBlockSize of its inbox
to zero when it gets a big batch of mail.  Of course, the app (and my
laola-based mailbox reader) is then unable to read the file.  AFAICT,
that is the only byte that is damaged, and it can be fixed after, but it
is annoying.

The app never did this before the patch, and hasn't since I reverted it
yesterday.

I will work on refining my observations, and I expect I will find and
fix the error eventually.  I'm just writing this in case it may be some
help to anyone.

Lawson