Issue #1985 resolved
Workbench: closing a branch commits changed but unselected files
Create a new branch in a repository containing files. Update your repo to this branch.
Modify an existing file on this branch.
Open Workbench. In the Commit view, ensure the file you modified is unchecked, i.e. should not be committed.
Click the Branch button in the commit view and select the "Close current branch" option.
Commit the changeset.
Expected result: Branch is closed without any file changes
Actual result: Branch is closed and the changed file becomes part of the commit