Sword taking damage when hitting another player with it when pvp is set to false

Iron sword taking damage when hitting another player with it when pvp is set to false

What I expected to happen was...:
I did expect that when I hit other player (in server) with iron sword when server's pvp is set to false, sword shouldn't take damage at all.

What actually happened was...:
When I hit my friend with my iron sword, my sword took damage.

Steps to Reproduce:
1. Me and my friend were playing on our server (pvp false). Our client and server version were 13w07a.
2. I had iron sword with only three uses left.
3. I hit my friend with sword three times and it broke.

You should also notice:
I'm not any kind of expert, but I think this would be pretty important bugfix because usually, in non-pvp servers, people hits each other with sword, for fun.