title: Source Control merge button grayed out?
body: <p>At my workplace we have set up GIT source control.
  We made a new branch off of the master and altered pretty much all of the code in a few modules. </p>
  
  <p>When we came to merge it the merge button in the source comparison window was greyed out?</p>
  
  <p>We had already made some changes in that branch and merged them, so would that stop us making other changers and merging the branch again?</p>
  
  <p>We're all pretty confused by this and kind of hoping somebody knows ANY reason why the merge button may be greyed out and we can see if that applies?</p>