After a stash branch merge, why doesn't my local repo show the branch has been merged?

[Adam Blair]

I have created a branch in stash, and merged it into master using the stash Pull Request/Merge process, and the master branch has all the right commits, so my code is fine.

However when I look at my local repo, the branch (that has now been merged) doesn't indicate that it has been merged (looking at the branch graph). When using other git hosts (e.g. github) the local repo shows which branches have been merged on the server. This is really useful as a quick guide to what peices of work have been completed and which are ongoing.

Am I doing something wrong in stash? 

Thanks, Adam