[issue18986] Add a case-insensitive case-preserving dict

[Antoine Pitrou]

Antoine Pitrou added the comment:

> FYI os.environ uses something similar: keys and values are encoded and
> decoded using functions. So any transformation is supported.

I don't think this is the same situation. os.environ has bijective
transformations, which don't pose any implementation challenge.

The whole point of a "transformdict" is to allow for multiple keys to
actually map to the same dict entry.

----------

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18986>
_______________________________________