Committed r66867. 

I had to considerably change the unit tests, because the subprocess 
output is not utf-8 encoded; it's not even the same as sys.stdout, 
because the spawned process uses a PIPE, not a terminal: on my winXP, 
the main interpreter uses cp437, but the subprocess says cp1252. So I 
first run a 'python -c "print(sys.stdout.encoding)"' in the same 
conditions just to retrieve the encoding. fun fun.
I hope this still works on Unixes, will watch the buildbots.