Last time I had to use Hg on a client project, disposable topic branches didn't seem to be something really supported. Broke our usual workflow and made a small mess for the client. Is this still the case?
Is there a reflog, though? When I mess up a git rebase, I have confidence I can always undo the rebase and try again.
When I used Mercurial, admittedly over five years ago, there wasn't a reflog. Sure, you'd get some .bak files when editing the history, but that's nowhere near as safe.
Have a branch-a that depends on branch-b that depends on branch-c that upstream just rebased and squashed some of its commits? More often than not `hg pull && hg evolve` is all you need to do to synchronise everything. This makes stacked PRs much easier to manage.