The deprecation shim created by Doug turns out to be rather useful.
It emits a warning when an global (attribute of a module) is
referenced but that global has been moved to another module.
This update makes the following changes to the shim:
- Rename it to _MovedGlobals to better describe what it is a
debtcollector for.
- Use inspect to get the original reference and to check that
_MovedGlobals is called from the last line of a module.
- Save the old reference automatically in the instance to prevent it
from getting garbage collected.
- Beef up the _moved_global() method for moving/renaming individual
globals, allowing it to move and rename or rename in place.
Change-Id: I868aa4a3129dd05467a103364088efbb86bc5d0f
99cfd671be