Looking over the 'display-warning' code, I realized that I had misread 
the docstring and wasn't calling it properly in Eshell. I gave these 
warnings a type of ':warning', but that's a warning *level*, not a 
warning *type*. Attached is a fix.

I'd like to merge this to the Emacs 29 branch. These are trivial fixes 
to a couple new features, and should make it easier for users to 
properly suppress these warnings if they choose to do so.