fix: git flow hotfix finish -b still back-merges to develop

[ChrisJStone]

https://github.com/petervanderdoes/gitflow-avh/blob/9d3592e7ee2bfa3df2d9c76885672b34ef12658f/git-flow-hotfix#L563

When git flow hotfix finish is passed the -b flag then it's not supposed to merge master to develop, but it does.

Steps:

git flow init -d
git flow hotfix start 1.0.1
git commit --allow-empty -m "hotfix commit"
git flow hotfix finish -b 1.0.1

The only difference between with and without -b is the way in which the merge is made to develop. What I want is for no merge to develop at all.