The logging of moderation reasons was wrongly using the _compose_reasons function and re-serializing the results afterwards, which caused log entries such as this:
HOLD: test@example.com post from anne@example.com held, message-id=<ant>: ; ; ; ; T; E; S; T; -; R; E; A; S; O; N; -; 1; \n; ; ; ; ; T; E; S; T; -; R; E; A; S; O; N; -; 2\n'This commit fixes it.