This variable is never used. Perhaps you wanted to use it in the ImportError? Otherwise, just delete this line please.
> def test_loading_from___init__(self):
Given this test doesn't actual load from __init__ but fails because that file is not there (after an explicit rename), I'd prefer a better test name, e.g. test_loading_from___init__only() say.
Some requested tweaks ...
> name = fullname[ len('bzrlib. plugins. '):]
This variable is never used. Perhaps you wanted to use it in the ImportError? Otherwise, just delete this line please.
> def test_loading_ from___ init__( self):
Given this test doesn't actual load from __init__ but fails because that file is not there (after an explicit rename), I'd prefer a better test name, e.g. test_loading_ from___ init__only( ) say.