Bug 2223 - lookup return garbage 
https://bugs.exim.org/show_bug.cgi?id=2223

lookups: fix mysql lookup returns for no-data "queries", when the number of rows affected is returned.
https://git.exim.org/exim.git/commitdiff/ba0e37b13c652435898f9b1050d6fe648875b125
https://git.exim.org/exim.git/commitdiff_plain/ba0e37b13c652435898f9b1050d6fe648875b125

https://git.exim.org/exim.git/commitdiff/ba0e37b13c652435898f9b1050d6fe648875b125#patch2
https://git.exim.org/exim.git/blob/ba0e37b13c652435898f9b1050d6fe648875b125:/src/src/lookups/mysql.c
https://git.exim.org/exim.git/blob_plain/ba0e37b13c652435898f9b1050d6fe648875b125:/src/src/lookups/mysql.c