Reset to alphabetical not working after clicking on the save button.

I created a new vocabulary and i ordered the terms using the reset to alphabetical button. The problem is when clicking on the save button the order of the terms is set back to way it was before i reset the terms to alphabetical.

Steps to reproduce:
1. Create a vocabulary
2. Create terms. I created a,b,c for this case.
4. Order them by b, c, a
5. Click on reset to alphabetical button - the terms are arranged to a,b,c
6. Click on the save button
7. The terms are set back to b, c, a

This is also occur on 7.x branch.