Both Survival and Creative

Put the summary of the bug you're having here

What I expected to happen was...:
A pair of villagers in a village with more than 10 doors should breed.

What actually happened was...:
Villagers wander around and go indoors at night, but don't reproduce. Occasionally some hearts will appear above one or other villager, but only last for a couple of seconds, sometimes less.

Steps to Reproduce:
1. Find or build a village.
2. Make sure there are enough doors to sustain a population of more than two.
3. Kill off all the villagers and either cure two zombie villagers or (in creative) use spawn eggs to create two.
4. Watch and wait. In survival I waited for three consecutive in-game days, no babies yet. I loaded up a copy of the world in 1.5.2, and the villagers bred within a couple of minutes. Trying again in 1.6, this didn't happen.