reverting back to the 1.3.8 version and re-applying the local Debian patch lets the powerpc testsuite pass. I didn't investigate any further.
see http://launchpadlibrarian.net/174189784/ruby-sqlite3_1.3.9-1_1.3.9-1ubuntu1.diff.gz -- To UNSUBSCRIBE, email to debian-bugs-rc-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org