git hf release cancel -f x.y.z does not delete local branch with changes

[ilyakam]

git hf release cancel -f ... does not delete the local release branch. Presumably that's because the local branch is unmerged, and the command to delete it uses the lowercase -d as opposed to the uppercase -D on the following two lines:

https://github.com/datasift/gitflow/blob/master/git-hf-release#L311
https://github.com/datasift/gitflow/blob/master/git-hf-release#L420

If my hunch is correct, I'll be happy to submit a PR that fixes this issue.

Steps to reproduce:

1. Create a new release branch (git hf release start 1.2.3)
2. Verify that a new release/1.2.3 branch has been created (git branch)
3. Bump the version number somewhere (e.g., CHANGELOG.md, package.json, etc.) and commit it
4. Cancel the release (git hf release cancel -f 1.2.3)
   • Notice the following line item in the summary of actions:
     Release branch 'release/1.2.3' has been deleted
   • Note that the local release branch has not been deleted (git branch)