A week ago I started a new branch in SourceTree by clicking the big Branch button, selected "New branch" and gave it name "#375". I then did a handful of commits before merging into the master branch by following the following procedure:
- Checked out the master branch
- Merged branch #375 into master branch
- Committed and pushed
Se image below. Why do I not see the blue line splitting into two lines at the "original branch point", and then being merged into one line again at the "merge point"?
I'm fairly new to both git and SourceTree, but I'm familiar with mercurial hg, in which this procedure was trivial. I was expecting the same procedure to work here. Help?

**Edit**: I realize I haven't done any commits on the master branch in the meantime, which may be the cause for it being invisible. Yet I'd still like to know the point at which I started branch #375 for historic reasons. For instance if I want to rollback the feature represented by this branch.