We used to always create a commitpartial file in child repo, because
ostree doesn't follow parent repos when loading commitpartial state,
and when the commit was in the parent repo it would find the commit
but no commitpartial and assume the commit was complete and do nothing.
However, having a commitpartial file seems to break delta downloads in
ostree, as per: https://github.com/ostreedev/ostree/issues/2053
causing us to download too much data when using deltas.
So, we now only create a commitpartial if there is one in the parent
repo. This still means we will get the ostree problems in case there
is one, but in the much more common case we avoid the issue.
In order to "fix" the uncommon case we also (separately) cap the
reported progress at 100%. (We should probably also fix the upstream
ostree issue too.)
3eaec588d7