Bugzilla Bug 182957

As the description says, I think it is better to let sys-fs/device-mapper
itself install the related udev rules file
/etc/udev/rules.d/64-device-mapper.rules. This ways the rules also can use the
new parameters dedicated for udev interfacing Kay added to device-mapper
without even more ugly version checks inside udev ebuild.

The move can be protected by blockers if necessary.
A. All older udev ebuilds blocking new added device-mapper ebuild.
B. New device-mapper ebuild blocking older udev ebuilds.

According to jakub we don't need blockers for CONFIG_PROTECTED files.
That means just adding the file to device-mapper will work.

@robbat2: Is it ok, that I just bump device-mapper to 1.02.19-r1 and add that
file?
And then either immediately, or some weeks later remove it from udev-ebuild.

zzam: Ok with me if you just add it via a bump.
Related question, how can we get it cleaned up for users that don't use
device-mapper (since udev won't add any new version, but the old one will
remain).

I suggest adding this to udev's pkg_postinst:
    # 64-device-mapper.rules now gets installed by sys-fs/device-mapper
    # remove it if user don't has sys-fs/device-mapper installed
    if has_version "<sys-fs/udev-113" &&
        [[ -f "${ROOT}"/etc/udev/rules.d/64-device-mapper.rules ]] &&
        ! has_version sys-fs/device-mapper
    then
            rm -f "${ROOT}"/etc/udev/rules.d/64-device-mapper.rules
            einfo "Removed unneeded file 64-device-mapper.rules"
    fi


And to catch the ugly case of emergeing device-mapper. Then udev-112-r1, and
then udev-113 I suggest to add this to pkg_preinst of udev to change mtime of
file, and portage will not remove it:

    if has_version "<sys-fs/udev-113" &&
        [[ -f "${ROOT}"/etc/udev/rules.d/64-device-mapper.rules ]] &&
        has_version sys-fs/device-mapper
    then
        # change mtime to definitely keep the file
        touch "${ROOT}"/etc/udev/rules.d/64-device-mapper.rules
    fi

Commited sys-fs/device-mapper-1.02.19-r1 and sys-fs/udev-113.

Move done!