Redmine#5271: pluck set_field_value

(cherry picked from commit 0c86e81b26caec135ca18f9b4d809e7d98ff6815)
Redmine#5271: do not INFORM erroneously if setting an empty field to an empty value, just note it in VERBOSE

(cherry picked from commit 454b28c6555ee04062e2e66db26c7d8e3f122474)