Ref T13462. Currently, when testing milestone edit policies during creation, the project object does not behave like a milestone:
- it doesn't have a milestone number yet, so it doesn't try to access the parent project; and
- the parent project isn't attached yet.
Instead: attach the parent project sooner (which "should" be harmless, although it's possible this has weird side effects); and give the adjusted policy object a dummy milestone number if it doesn't have one yet. This forces it to act like a milestone when emitting policies.