typing: make `bundlerepository` subclass `localrepository` while type checking Currently, `mercurial/bundlerepo.py` is excluded from pytype, mostly because it complains that various `ui` and `vfs` fields in `localrepository` are missing. (`bundlerepository` dynamically subclasses `localrepository` when it is instantiated, so it works at runtime.) This makes that class hierarchy known to pytype. Having a protocol for `Repository` is probably the right thing to do, but that will be a lot of work and this still reflects the class at runtime. Subclassing also has the benefit of making sure any method overrides have a matching signature, so maybe this is a situation where we do both of these things. (I'm not sure how clear the diagnostics are if a class *almost* implements a protocol, but is missing a method argument or similar.) The subclassing is not done outside of type checking runs to avoid any side effects on already complex code.