Somebody pushed a branch called test with git push origin test to a shared repository. I can see the branch with git branch -r.
If the branch is on something other than the origin remote I like to do the following:
$ git fetch
$ git checkout -b second/next upstream/next
This will checkout the next branch on the upstream remote in to a local branch called second/next. Which means if you already have a local branch named next it will not conflict.
$ git branch -a
* second/next
remotes/origin/next
remotes/upstream/next