It is quite common to pre-load libraries into existing binaries e.g. for 
profiling  Typically, those write to stdout or stderr only if the option 
for an output file is not used.  That is how I happened to run into the 
issue the other day.

For a while, the initial symptoms looked like the different exit 
behavior in 3.0a1 might be a serious problem.  It was not obvious that  
stdout and -err might have been closed and caused the difference.  All 
the Python 2.x versions never closed stdout and -err.

Therefore, 3.0 should probably not do that either.  But that is really 
your call.