Minecraft wiki entry for Development_versions, associated text: They will now react positively on new trades, and negatively if you hurt them.
This effect only takes place if the villager recognizes nearby housing, most commonly with naturally spawned villagers.
There is an unused particle effect added of a villager's face looking angry.
They will no longer remove trades, but trading something else may be required to renew the old ones.
Several trades had their quantities altered:
The farmer's gravel & emerald trade now produces 4 or 5 flint, up from 2 or 3 flint before
The librarian's buy paper trade now requires 24 to 35 paper, up from 19 to 29 paper before
The librarian's buy book trade now requires 11 to 12 books, down from 12 to 14 books before
The farmer's buy arrow trade now sells 9 to 12 arrows, changed from only 5 arrows before. The 5 arrows resulted from a bug in the code where the minimum and maximum values for the arrow trade were swapped.