Message 129227 - Python tracker

$ ./python.exe -m timeit "b'x'.decode('latin1')"
100000 loops, best of 3: 2.57 usec per loop
$ ./python.exe -m timeit "b'x'.decode('latin-1')"
1000000 loops, best of 3: 0.336 usec per loop

The reason for this behavior is that 'latin-1' is short-circuited in C code while 'latin1' has to be looked up in aliases.py.  Attached patch fixes this issue.