title: Git says branches are both the same and different
body: <p>I don't have much experience with git, so forgive me if this is obvious. I had an issue when merging 2 branches. I have 3 branches: development, uat and master. In CLI, if I type "git diff development..uat", it is blank. If I do the same thing with either dev/uat to master, there are pages of diffs displayed. However, when I put "git merge --no-ff uat", it says this branch is up-to-date. Ultimately, I want  Master to be exactly the same as the code in both dev and uat. When I merged in gitlab, it merged only the last commit. I can physically go through the code in gitlab and see the differences, yet it tells me when I try to merge there that all branches are identical. Am I missing an obvious solution? Is there some way to force Master to accept the changes?</p>
  
  <p>I looked at <a href="https://stackoverflow.com/questions/39467880/why-is-git-merge-saying-two-branches-are-up-to-date">Why is git merge saying two branches are up-to-date?</a> but the situation didn't seem to be the same, nor did they actually tell the asker what the solution was.</p>