Comment 10 for bug 1741096

the recreate script demonstrates failure on xenial, artful and bionic in a VM.
xenial needs a change to mount-image-callback to run 'blockdev' on the nbd device. i'm not actually sure how i've never seen that bug before.

with the change in place, all 3 can be made to show the issue. artful and bionic vms are actually somewhat reliable, but if you run two copies of the script concurrently it will fail.

=== modified file 'bin/mount-image-callback'
--- bin/mount-image-callback 2018-01-03 15:44:47 +0000
+++ bin/mount-image-callback 2018-01-04 17:19:37 +0000
@@ -316,6 +316,7 @@
        fi

        i=0
+ [ -b "$mdev" ] || blockdev --rereadpt $nbd
        while :; do
                [ -b "$mdev" ] && break
                i=$(($i+1))