Avoid rebuilding tree twice if two processes notice it's broken at the same time.
Avoid rebuilding tree twice if two processes notice it's broken at the same
time.

LTD-Beget/dovecot,damoxc/dovecot,LTD-Beget/dovecot,Distrotech/dovecot,damoxc/dovecot,damoxc/dovecot,Distrotech/dovecot,LTD-Beget/dovecot,damoxc/dovecot,LTD-Beget/dovecot,Distrotech/dovecot,Distrotech/dovecot,damoxc/dovecot,Distrotech/dovecot,LTD-Beget/dovecot