tla takes backup of logfile as commit logfile

Hi,

A colleague of mine I convinced to try out tla is having this weird
problem I don't understand. Thanks in advance for any help.

When he does "tla commit", tla silently takes the editor backup of the
log of the _previous_ commit (named ++log.blahblah~) as log. This is
reproducible always in his working directory of his only tla-managed
project.

But if he or I create(s) a new project within a new archive on the
same machine using the same editor to edit the log to test things out,
we cannot reproduce the problem. I tried copying over his
{arch}/=tagging-method file, thinking that maybe this influenced it,
nope, still cannot reproduce the problem. If I fork a branch in my own
archive of the project he is having the problem in, I can't reproduce
the problem.

Any idea?

-- 
Lionel