Game freezup, infinate Pig generation

Put the summary of the bug you're having here

What I expected to happen was...:
Describe what you thought should happen here
Return to a village and interact with the villagers.
What actually happened was...:
Describe what happened here
The village was populated with an extremely large number of pigs, that were not present when The village was last visited. Most time in game had been spent more than 500 blocks away from the village
Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...The game locks up any time that world is opened

3. ...