This removes the invalid revision parents references.
This touches slightly the revision_*log tests because the arborescence
revision, to be correct, is now a bit more involved.
from:
rev4 -is-child-of-> rev3 (stop)
becomes:
rev4 -is-child-of-> rev3 -> rev1, rev2; rev2 -> rev1
Related to T2494
Depend on D3585