Wording in `mypy.plugin.Plugin.get_method[_signature]_hook` docstring

Documentation

The docstring of these plugin hook methods currently say:

https://github.com/python/mypy/blob/057508b4cb405fbc22e26b44f764b142352fcce5/mypy/plugin.py#L647-L648

...

https://github.com/python/mypy/blob/057508b4cb405fbc22e26b44f764b142352fcce5/mypy/plugin.py#L664

I understand this to mean that the argument to fullname will be "__main__.Base.method", because __main__.Base defines method.

However, this doesn't seem to be the case. Setting up the same example in the docstring:

• mypy.ini

  [mypy]
  plugins = plugin.py
  files = test.py
  

• plugin.py

  from mypy.plugin import Plugin
  
  def plugin(version):
      return TestPlugin
  
  class TestPlugin(Plugin):
      def get_method_signature_hook(self, fullname):
          if fullname.startswith("test."):
              print(f"Hook will be called with `{fullname}`")
  

• test.py

  from typing import Any
  
  class Base:
      def method(self, arg: Any) -> Any: ...
  
  class Derived(Base): ...
  
  var: Derived
  var.method(42)
  

$ mypy
Hook will be called with `test.Derived.method`

I installed as far back as mypy 0.9x and it was the same behaviour as described above, displaying test.Derived.method (not test.Base.method).

Is there something wrong with the docstring (perhaps from outdated behaviour that no longer applies), or have I misunderstood something?

Start with the linked hook docstrings in mypy/plugin.py around lines 647-648 and 664, then reproduce the supplied mypy.ini, plugin.py, and test.py example. Compare the documented fullname with the observed test.Derived.method value; the work is done when the docstring accurately explains the hook argument or the reported misunderstanding.