Remove duplicate method

This should fix static analysis.

qa/qa/git/repository.rb

@@ -96,10 +96,6 @@ module QA
         run("git merge #{branch}")
       end
 
-      def merge(branch)
-        run("git merge #{branch}")
-      end
-
       def commits
         run('git log --oneline').to_s.split("\n")
       end