Mercurial wipes repository history!?

[Jon Ribbens]

Is it just me, or is this very, very bad?

$ hg version | head -1
Mercurial Distributed SCM (version 1.5)
$ hg -q clone ssh://hg@hg/audit
$ cd audit
$ hg log | wc -l
4828
$ hg rollback
rolling back last transaction
$ hg log
$ find .hg/store/data -type f
$ 

You may well say why am I rolling back immediately after a clone, but
(a) it still shouldn't wipe the repository and (b) the above is just
an attempt to replicate a wipe that happened under more complicated
circumstances involving a rollback after a "pull -u" with a dirty
working directory. Also the behaviour is different if the parent
repository is local not remote - the rollback just says it has no
rollback info and does nothing.