[syslog-ng] subst() pcre escape sequences

Ok, I'm trying to lowercase a certain macro with a pcre rewrite rule. Unfortunately it doesnt seem to be observing pcre escape sequences. subst('^(.+)$','\L$1\E',value('FROM') flags('store-matches') type('pcre')); (the FROM macro is created from the named match of an earlier pcre filter() It ends up just putting a literal '\L' and '\E' at the start and end of the string. Is this a bug, or am I doing something wrong, or is there another way to do this?