The "unreleased" file being empty causes the releasenotes
job to fail with:
Warning, treated as error:
source/unreleased.rst:13:
WARNING: Inline interpreted text or phrase reference start-string
without end-string.
Change-Id: Ia5c2f2cf9ff37b5ec3f9e717a90b977d1e79b530
85b7fd85b5