Number of votes after a rollback isn't correct

[ane-gabriela]

1. Create a new idea
2. Vote Yes
3. With the same user, switch and vote No
4. Make a rollback from last to previous version
5. Check the votes in Ideas live table

Expected results: The vote displayed is Yes, which was the previous vote.

Actual results: After the rollback 2 votes appear: 1 for Yes and 1 for No, with the same user.

https://jira.xwiki.org/browse/IDEAS-64