As Dashamir Hoxha in the mailinglist gnupg-users mentioned, even with the
--quiet flag enabled, there still is logging output after/during the validation
of the trust-db.

When the user enables the --quiet flag, there should be no log_info output to
the stdin. At most points in the code its managed like in ./g10/trustdb.c:970
(Commit b752d2c93778e6a1c1de3eddf8fc725b0ddd354e in master from the public Git).
But after the silenced output there, it goes into the validate function, where
still is a log_info output in ./g10/trustdb.c:2057 (Same commit as mentioned
above).

relevant to T1424

Fixed on 2016-03-19 with commmit af9a4afb. Note that --quiet shall not suppress
all output.

(The commit you gave is wrong).