Subversion shop considering switching to Mercurial, trying to figure out in advance what all the complaints from developers are going to be. There's one fairly common use case here that I can't see how to handle.

1. I'm working on some largish feature, and I have a significant part of the code -- or possibly several significant parts of the code -- in pieces all over the garage floor, totally unsuitable for checkin, maybe not even compiling.
2. An urgent bugfix request comes in. The fix is nice and local and doesn't touch any of the code I've been working on.
3. I make the fix in my working copy.

Now what?

I've looked at "Mercurial cherry picking changes for commit" and "best practices in mercurial: branch vs. clone, and partial merges?" and all the suggestions seem to be extensions of varying complexity, from Record and Shelve to Queues.

The fact that there apparently isn't any core functionality for this makes me suspect that in some sense this working style is Doing It Wrong. What would a Mercurial-like solution to this use case look like?