moss does not work when run from chroot (via arch linux)

[jplatte]

As noted in #302, I'm getting the following error:

Error: sync: client: postblit: container: exited with failure: pivot_root: EINVAL: Invalid argument

when trying to install or update a package with moss when chroot'ing from my main Arch Linux install into Serpent OS. The same commands succeed when I boot into Serpent OS instaed (modulo actually downloading stuff, because WiFi is broken).

I briefly had a look at the docs for pivot_root and found this error condition:

EINVAL The current root directory is not a mount point (because of an earlier chroot(2)).

which seems like it could be the reason that things are breaking?

This is of course just a minor inconvenience in fudging around with Serpent OS, but I thought it wouldn't hurt to have an issue pointing it out :)