Comment # 1 on bug 1191945 from Ignaz Forster

If I understood Fabian correctly this doesn't happen every time?

That's interesting, because I didn't change the mount behavior of *those*
directories in the latest updates (though I did some mount optimizations in
other areas).

Let's try with a different approach then, which was originally supposed to go
into the 4.0 release, but I may also pull this into the 3.x series: Instead of
mounting everything twice (once into /.snapshots and then bind mounting
everything into a temporary directory) just use the temporary mount point. I
will do a new transactional-update release in a few minutes.

If that also doesn't work I will set up a private mount for separate mount
namespaces.