$ darcs --version
2.9.1 (+ 14 patches)

$ darcs amend --edit
Pick patch to amend (newest patch in my case) and then answer 'n' to all
working-dir changes (there was only one in my case)

Now, I get the "Do you want to add these changes?" prompt; if I say 'y',
then I get taken to the message-editor, as desired, but if I answer 'q'
darcs says "add cancelled". 

So, 2 things:
1) If I say n to all patches, then I don't want prompting by
last-regrets since I've not picked anything to add to my patch.
2) If I say q to "Do you want to add these changes" I'd rather darcs
says "amend cancelled" than "add cancelled" (even though I know
technically I'm doing an add at that point, under-the-hood.

Regarding (1), answering 'd' to the first working-dir change skips the 
last regrets prompt.  I agree that it should do the same if all answers 
were 'n'.

This the sort of thing we should have tests for?  Not the language so much 
as the behaviour.  I suspect so, as there could be lots of little edges we 
want to match out for