my repo says: remote: abort: abandoned transaction found!

Here's a transcript from my terminal:

hg push --new-branch -r tip ssh://hg@bitbucket.org/cameron_simpson/css
pushing to ssh://hg@bitbucket.org/cameron_simpson/css
searching for changes
remote: abort: abandoned transaction found!
remote: (run 'hg recover' to clean up transaction)
abort: stream ended unexpectedly (got 0 bytes, expected 4)

Please repair this. It would be useful if we could repair this kind of thing ourselves.

Thanks, Cameron Simpson