There's a fix in the testing branch, just haven't bothered putting out a build. Open source and all you know, build it yourself blah blah. If you can't build from source, you're at my mercy blah blah.
Progress! I built the testing branch, now, right clicking and selecting bump fee shows a dialog that says:
RBF Failure: You are trying to bump the fee of a broadcasted unconfirmed transaction. The process failed unexpectedly. To double spend your transaction, pick the relevant output from the RBF Control, found in the Send dialog in Expert User Mode.
Clicking "ok" leads to the send dialog. I clicked on the RBF Control button and reviewed the outputs, went back to the send dialog and lowered the send amount. Clicking send results in an error message:
Coin Selection Failure: Coin selection failed with error: Invalid spend value
goatpig, please explain a little more what I need to do, thanks!