And it shows up in the bugs and problems that are posted to the bazaar
list. Eg, I have never seen a wedged git or hg repository or branch;
it is *always* possible to get back to where you started from (unless
the content storage itself is corrupted). The worst that can ever
happen (unless you explicitly type "git commit" to make the mess
permanent) is that you've wasted hours trying to resolve an insane
merge conflict. But people post regularly (recently, I'd say about
once a month) asking how to get some previous version (in some cases,
any version at all) checked out of their bzr branch. And in some
cases the answers are very non-trivial (writing a plugin for bzr that
replaces buggy functionality, for example).
These are bugs, of course, but they're unimaginable in git or hg,
because the history data is wedged, not the content storage. With the
history data used by git, at least, wedging the history would be as
criminal as wedging a list in Emacs LISP would be. But wedged history
*is* occasionally reported for bazaar.