This is the situation:
repo    upstream     upstreamfork      myfork_from_upstreamfork
branch   master         testing             mybranch
           |
           |
           |-------------->|
                           |------------------->|
                           |
                           |
upstreamfork has new commits. I need to update mybranch from myfork_from_upstreamfork with the latest commits from upstreamfork/testing
I tried git rebase upstreamfork/testing from mybranch, but I get
Current branch mybranch is up to date.
How do I correctly update my branch?
I am starting fresh on this project. Eventually I will issue PRs for upstreamfork - which may well be integrated into upstream at some point - so I don't want to mess up :shiver
 
    