Theres a 0.7% chance of any colored roped villager (else than green roped villagers of course) turning into a green roped villager when updating to 1.6.2

What I expected was nothing.
What happen was that the villagers turned to green roped villagers.
Step 1. Spawn 47 villagers in 1.5.2.
Step 2. Update to 1.6.1.
Step 3. Update to 1.6.2.
Enjoy!