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

This may not work for you guys but when I spawned 47 villagers in 1.5.2
and then updated 1.6.1 nothing happen and I was waiting for 1.6.2 to come out and when it came out 5 of my villagers was green roped eventhough theyre not usually green.

Nothing Mojang can do now.

also you can summon it in 1.7.10 /summon Villager ~ ~ ~ {Profession: 5}