The value *for this key* is a dot separated sequence of integer labels in a string. The limit of that is a single integer label that could be converted to a Python int. 

With the current patch get_config_var('MACOSX_DEPLOYMENT_TARGET') mostly returns a string, but sometimes an integer.  And the last part is new behaviour, which means existing consumers of this won't be prepared to handle a non-string value (other than None).

I'll probably create an alternative PR this weekend.


sysconfig converts config values that look like integers to python ints because that's often useful, but in this case it isn't. This part of the code base is old and has not very well defined semantics.