Comment 7 for bug 1777636

I've rerun on autopkgtest for one of the 4.15 kernels with -proposed enabled, and confirm that it does now pass:

https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-xenial/xenial/amd64/d/dm-writeboost/20181206_161004_9d437@/log.gz

Marking this verified and releasing.