Strange Barn Swallow (1 Viewer)

My friend saw this swallow in the northeast of Iran. I did not see this individual but there were some breeder Barn Swallows. The white neck ring and the white back and rump are not usual. I asked from Iran Bird Committee and they answered they don have such record before.
Is it a hybrid with Red-rumped Swallow or a mutation? Please help us with understanding more about this Barn Swallow.

Looks like partly leucistic Barn Swallow to me.