SaltStack uses Python subprocess and redirects stderr to stdout which is
then piped to the returned output. If php-fpm starts in daemonized mode,
it should close stderr. However a fix introduced in GH-8913 keeps stderr
around so it can be later restored. That causes the issue reported in
GH-9754. The solution is to keep stderr around only when php-fpm runs in
foreground as the issue is most likely visible only there. Basically
there is no need to restore stderr when php-fpm is daemonized.
Máté Kocsis