I took a quick peruse around and didn't see this as previously reported.
Ignition 8.1.45
I was converting a message handler to a custom script as it didn't need to be a message handler so I copied over the code and then copied the name and I noticed it didn't rename the function. Instead it left it as def (self):
If you hit okay or apply it does indeed apply the name, but interesting that I have never noticed it before. 
