When setting cache corrupted, make sure we don't write broken values to the new cache file. Also log broken virtual size fetches better and support 0 as a generic "some fields" value.
When setting cache corrupted, make sure we don't write broken values to the
new cache file. Also log broken virtual size fetches better and support 0 as
a generic "some fields" value.

--HG--
branch : HEAD

jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jwm/dovecot-notmuch,jkerihuel/dovecot,jwm/dovecot-notmuch,jkerihuel/dovecot,jkerihuel/dovecot