This is necessary in order to create models on-the-fly within tests and
to test improper Model / Field creation: registry.reset_changes will
only perform the reset of the registry if it is invalidated, however if
the setup of models crashes before it is invalidated (as is the case of
a test), the reset_changes will not be triggered and thus the registry
will be left dirty for subsequent tests.
Adrian Torres
96223568c4