Resolve the following RemovedIn20Warning warning:
Calling .begin() when a transaction is already begun, creating a 'sub'
transaction, is deprecated and will be removed in 2.0. See the
documentation section 'Migrating from the nesting pattern' for
background on how to migrate from this pattern.
Change-Id: I59e45dfea8fcbf72fc6e34345e510554cbdd138e
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>