lib-storage: Don't fail if messages are expunged during counting mailbox's virtual size.
lib-storage: Don't fail if messages are expunged during counting mailbox's virtual size.

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