Dovecot 2.2.36 + Pigeonhole 0.4.24

Is this an intended behavior?

# service dovecot status
dovecot is stopped
# doveconf mail_plugins
mail_plugins =  stats
# ls foo.*
foo.sieve
# sievec foo.sieve
sievec(root): Error: stats: open(/var/run/dovecot/stats-mail) failed: No such device or address
# echo $?
0
# ls foo.*
foo.sieve  foo.svbin

-- -- Name: SATOH Fumiyasu @ OSS Technology Corp. (fumiyas @ osstech co jp) -- Business Home: https://www.OSSTech.co.jp/ -- GitHub Home: https://GitHub.com/fumiyas/ -- PGP Fingerprint: BBE1 A1C9 525A 292E 6729 CDEC ADC2 9DCA 5E1C CBCA