.mew-alias gets lost occasionally

[pipapu]

I am running mew 6.7 on Emacs 24.5.1 under Ubuntu Linux 15.10.

My .mew-alias file occasionally gets lost: I find that email address expansion using [TAB] does not work as expected, and then I see that the .mew-alias file has gotten very small and contains only few
entries. If I notice it early enough, .mew-alias.old still contains the full information, but often I don't. Then I need to restore .mew-alias from a backup.

Unfortunately, I cannot pin down the precise conditions when this happens. I guess it is related to system or X.org crashes, but I just tried killing an active mew session doing "killall -9 emacs", and in this case .mew-alias did not get lost. So, it must be something more complicated, perhaps a race condition.

From my automatic backups, I see that the problem started exactly at the time of the upgrade to mew 6.7 (not 6.6) and persisted since then.

Further, my automatic backups indicate that, when .mew-alias gets lost, the file .mew-alias gets "deleted" (which probably means it does not simply get overwritten or it does not get re-created fast enough for my backup program not to notice).

Hope this helps to narrow down the problem. Let me know if you need me to do some more tests.