I see. From my Debian packaging experience this suggests libdevmapper/dmsetup would have to have a "Replaces:" and/or "Conflicts:" in it's control file for the OLD easy-chroot package. Without it, the order of installs influences the outcome (if easy-chroot gets upgraded first, libdevmapper is OK, if libdevmapper comes first, it errors -> that's why it works out on the second try). Can you tell me the versions you used in easy-chroot (i.e. which is the last old-style package ver) ?