Water/Sign Bug,

*What I expected to happen was...:
The water that i cut off with a sign, should dissapear after the sign.

*What actually happened was...:
It didn't, it just keep flowing. After the sign.

*Steps to Reproduce:
(Or watch the attachment)
1. Place water
2. If the water is flowing minimal 2 blocks.
3. Cut it off
4. Water keeps flowing "Thru" the sign.