For RHEL 7.5 (comes out sometime in April-2018), the following Nova
upstream commit should be backported to RHOS-10 (given its long-term
support cycle):

    commit 807579755c4a116309eca5b2bcdbab9d1f393bab
    Author: Matt Riedemann <mriedem.os>
    Date:   Wed Sep 20 10:44:11 2017 -0400

        Support qemu >= 2.10

        Qemu 2.10 added the requirement of a --force-share flag to qemu-img
        info when reading information about a disk that is in use by a
        guest. We do this a lot in Nova for operations like gathering
        information before live migration.

        [...]

RHEL 7.5 will ship with QEMU 2.10, which will bring in an additional
flag '--force-share' — this is mandatory when running `qemu-img info` on
a live Nova instance.

Nova does this `qemu-img info` call in several places.

This change needs to be backported to RHOS-10, given its support life-cycle:

    RHOS-10: End of Production, Phase 2: December 16, 2019