Description of problem:

Originally as https://bugzilla.redhat.com/show_bug.cgi?id=1425788 but now taking into account that engine channels in d/s contain $MAJOR.$MINOR in their names.


3.6 engine can't be restored in 4.1.

~~~
# sed -n -e '/^VALID_BACKUP_RESTORE_PAIRS/,+3p' -e '/^verifyVersion/,/^}$/p' `which engine-backup`
VALID_BACKUP_RESTORE_PAIRS="3.6 4.0"
# A newline-separated list of pair. E.g. if we want to allow 4.0->4.1,
#VALID_BACKUP_RESTORE_PAIRS="3.6 4.0
#4.0 4.1"
verifyVersion() {
set -x
        INSTALLED_VERSION="$(echo ${PACKAGE_VERSION} | cut -d . -f 1-2)"
        BACKUP_VERSION="$(cat ${TEMP_FOLDER}/${PACKAGE_VERSION_FILENAME} | cut -d . -f 1-2)"
        local ok=
        while read validbck validres; do
                [ "${BACKUP_VERSION}" = "${validbck}" -a "${INSTALLED_VERSION}" = "${validres}" ] && ok=1
        done << __EOF__
${VALID_BACKUP_RESTORE_PAIRS}
__EOF__
        [ "${INSTALLED_VERSION}" == "${BACKUP_VERSION}" ] && ok=1
        [ -z "${ok}" ] && logdie "Backup was created by version '${BACKUP_VERSION}' and can not be restored using the installed version ${INSTALLED_VERSION}"
}
~~~

~~~
# cat restore.log 
2017-02-22 13:38:09 1875: Start of engine-backup mode restore scope all file backup
2017-02-22 13:38:09 1875: OUTPUT: Preparing to restore:
2017-02-22 13:38:09 1875: OUTPUT: - Unpacking file 'backup'
2017-02-22 13:38:09 1875: Opening tarball backup to /tmp/engine-backup.ZHol45Ydri
2017-02-22 13:38:09 1875: Verifying md5
2017-02-22 13:38:09 1875: Verifying version
2017-02-22 13:38:09 1875: FATAL: Backup was created by version '3.6' and can not be restored using the installed version 4.1
~~~

Version-Release number of selected component (if applicable):
ovirt-engine-tools-backup-4.1.1.2-0.1.el7.noarch

How reproducible:
100%

Steps to Reproduce:
1. test if 3.6 engine backup can be restored in 4.1
2.
3.

Actual results:
not possible now

Expected results:
it would be nice to have

Additional info: