[patch] [python] Implement Inferior.current_inferior

[Joel Brobecker]

> Whether your patch, or mine makes it in I don't mind.  The patches looks
> similar, but mine has a few extra tests and accounts for the reference
> leaking/sigsegv.  I would be happy to add your name to the ChangeLog as
> co-implementer if the maintainers think this is ok (and they approve the
> patch).

It could be a merge of the two patches, with both names on the CL,
I think.

-- 
Joel