Avoid reloading builtin types module.

[Carreau]

Closes #10235

[takluyver]

Bit disturbing that the exclude list doesn't work for this.

I'd like to find a way to exclude all standard library modules from deepreload(), but I don't know of a good way to check if something's in the stdlib.

Maybe the rule should be 'anything that IPython uses' - i.e. anything that's in sys.modules before user code runs. It's possibly tricky to do that now that we don't load deepreload on start.

[Carreau]

I'd like to find a way to exclude all standard library modules from deepreload(), but I don't know of a good way to check if something's in the stdlib.

There isn't. And AFAICT Core python does not see any interest in doing it. We could check early-python-modules that have the specific file _bootstrap_external_something.

I've looked as to where the NotImplementedError but that's too far down in CPython, I I don't understand the real reason why it hits this spot. And exclude does not work, because it work on module names, and the current code fails when trying to get the modulename (via find_spec), so it does not have a chance to exclude it...

I honestly think it might be a Bug in CPython itself. But it would be nice to even have a band-aid potentially opening an issue to investigate later.