We've been fighting some weird regressions in the test cases for the Block class which handles IP & user blocks, some of which took us a while to even reproduce consistently. After Chad & others cleaned up some sqlite-related issues, we still had a remaining stubborn one which failed in the full test suite, but not when run standalone.
Between me, Mark H, and Chad, we seem to have finally worked that one out today, and made some fixes to both Block and BlockTest which have resolved it.
Full story if you like. :D -> http://etherpad.wikimedia.org/Block-test-bug
Short story: http://ci.tesla.usability.wikimedia.org/cruisecontrol/buildresults/mw
"Unit Tests: (1628) All Tests Passed "
*break out the virtual champaign*
-- brion