To close a issue in Github via a PR you just need to add a key phrase like:
Closes #100
in the body of your PR and as soon as PR is merged into the default branch Github automatically closes the issue.
We merge our PR into branches under a version number (say branch 2.0.0). but the issue remains open until we merge it into the default branch (in our case development).
My question is how to setup the branch and/or PR so that after merging the PR into the (non-default) target branch, it closes the issue automatically.