rebase with no changes

[simonwiles]

I regularly run into the situation where I rebase one branch on another, and resolve conflicts by completely scrapping changes on the checked out branch. At this point, I can't continue with the rebase, and git gives the message "No changes - did you forget to use 'git add'?". The resolution is to use git rebase --skip on the command-line, but it would be nice if ungit presented this option.

See related: #1097.

Thanks!