Fix extra space added in beginning of commit message

Removes extra space in merge commit messages. This seems to have been introduced by the functionality added in 38d8d749d which allows a user to change a merge commit message.

This is probably not the greatest way to fix this but feel it is worth showing what I did to fix in the interim.

Before:
![broken](https://f.cloud.github.com/assets/3237256/2253523/71d3613e-9dc0-11e3-87d3-137859f9fe02.PNG)

After:
![after](https://f.cloud.github.com/assets/3237256/2253525/7bbcb6fa-9dc0-11e3-8ebc-fdc3e02714ad.PNG)