Abort if the release specification is cleared entirely

In Git, when you start a rebase, you can delete all lines if you've changed your mind and no longer wish to proceed. This tool should work the same way with editing the release specification. (Note: deleting all lines technically does work to abort, but it throws an error instead of just saying "Aborting".)

No file, test, or entry point is named in the issue. Start by locating the command handling edits to the release specification and reproduce the empty-specification case; done means deleting every line cleanly reports "Aborting" without an error.

Written by the indexing model from the issue text.