On CPython this code prints "Pass" and on IronPython it prints "Fail".
 
 
import bisect
 
class CmpErr:

"Dummy element that always raises an error during comparison"
def __cmp__(self, other):
    raise ZeroDivisionError

seq = [CmpErr(), CmpErr(), CmpErr()]
 
try:

bisect.bisect_left(seq, 10)

except ZeroDivisionError:

print "Pass"

else:

print "Fail"

 
It looks like the comparison code that is generated is not doing the correct thing compared to the rich comparison in CPython.