Fix to delayed cache file opening, cached data might have been lost.
Fix to delayed cache file opening, cached data might have been lost.

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branch : HEAD

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