[issue15122] Add an option to always rewrite single-file mailboxes in-place.

[Petri Lehtinen]

Changes by Petri Lehtinen <petri at digip.org>:


----------
components: +email
nosy: +barry, r.david.murray

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15122>
_______________________________________