Put the summary of the bug you're having here

Normally, players can't walk through the gaps in between fences. But in the new snapshot, my animals and I were able to clearly escape through the gaps

No player should be able to walk fences on the same kind, but 14w26a allows it and this is a MAJOR bug

1. Make a line of wood fences
2. Press yourself against the fences
3. Walk while leaned against them and you will find that you can easily walk through