Objects with a custom __setattr__ could impact spies, if they don't

fall back to the default behavior. In some cases, we attempt to set a

cloned method on an instance, and this triggered __setattr__,

sometimes losing that spy and leading to various sorts of failures.
We now explicitly call the default object.__setattr__() for instances,

which ensures we're setting the value in the instance's dictionary

instead of triggering the subclass. This is effectively what setattr()

would do by default.

Ran unit tests on all supported Python versions. They failed prior to the

fix, but ran successfully after.
Hit this issue during development on another project. Verified that the

problems went away after the fix.