Currently if the user decides to do an interactive rebase, the UI breaks and the user is presented with 'noop'.

Rather SourceTree should, at minimum, use a real error message, for example

'this tree has already been merged. Rebasing would change what's already been pushed upstream. if you'd like to rebase anyway, right click a commit and choose 'rebase children interactively'

Or some thing else - anything would be better than no-op.