Commit hook looks at current state of files rather than state of added files

[maartenflippo]

Running the commit hooks does not necessarily prevent committing with unformatted code since it only looks at the current state of the repository. Thus the following situation can occur:

• Attempt to push a commit and get an error that files are not properly formatted
• Fix the issues and commit again
• Forget to run git add and the commit hooks pass even though the committed files are unformatted
• Push unformatted code to the repository