This updates the git-flow-avh plugin to the latest version from https://github.com/petervanderdoes/git-flow-completion (0.6.0 at the time of this commit). This mainly adds support for the "git flow bugfix" command. This PR replaces #4626 as well as #4705, both of which adds support for the bugfix command but doesn't use the official version from https://github.com/petervanderdoes/git-flow-completion Fixes #4705 Fixes #4626 Fixes #5903