Why does git merge sometimes create a commit, sometimes does not?

Question

When I do git merge from another branch to current workspace, git sometimes makes a new commit:

Merge remote-tracking branch xxx into xxx
         


        

Answer 1

When no fast-forward --no-ff option is presented git will not create a commit if the head of the branch you are merging in is the ancestor of the merged branch. In this case (no --no-ff option) it will just move the head (it's a fast-forward).