Backported 1.39 and 1.40 from trunk: 1.39: Fix SF bug 610610 (reported by Martijn Pieters, diagnosed by Neal Norwitz). The switch in Exception__str__ didn't clear the error if PySequence_Size() raised an exception. Added a case -1 which clears the error and falls through to the default case. 1.40: Two more cases of switch(PySequence_Size()) without checking for case -1. (Same problem as last checkin for SF bug 610610) Need to clear the error and proceed.