An error was raised by libgit2. Category = 21 (MergeConflict)

Looks like running git pull from the command prompt allowed me to execute the pull. I was unfamiliar with the command prompt.

Typically, you will see this message when you have modified a file, but not staged the changes, and the merge you are attempting would write to that file. Visual Studio 2013, unfortunately, contains a bug where it determines that your file is modified even though it is not. The bug manifests when you have a file in your repository that has line endings that disagree with what should have been produced, given your core.autocrlf settings.

This bug is fixed in Visual Studio 2013 Update 2: http://support.microsoft.com/kb/2927432