[Bug]: Backend name specified as module gets lowercased since 3.9 #28432
Description
Bug summary
MPLBACKEND="module://foo.Bar" now tries to import the foo.bar module as opposed to foo.Bar, as before.
Code for reproduction
MPLBACKEND="module://foo.Bar"Actual outcome
foo.bar is imported
Expected outcome
foo.Bar is imported
Additional information
This probably regressed in #27948.
Operating system
Fedora Linux 39
Matplotlib Version
3.9.0
Matplotlib Backend
No response
Python version
No response
Jupyter version
No response
Installation
None