Comment 9 for bug 1070008

http://anonscm.debian.org/gitweb/?p=buildd-tools/schroot.git;a=commitdiff;h=02fa2aefc24e95852aa991f720b3c9dc53583d1c

Note that this patch needs backporting to the schroot-1.6 branch and testing with all block-device-using chroot types before I would recommend applying it. **Please do not apply this until it is fully tested.**