Re: libostree v2017.8

[Colin Walters <walters verbum org>]

For anyone who was having trouble accessing the github release;
turns out I screwed it up and had `v2018.8` as the release name (different
from the tag), and github pushed that as a new tag.

I hadn't realized that and later did:
git push origin :v2018.8
which undid the release (but not the original v2017.8 tag).  But I had
thought that the v2018.8 was me somehow typo'ing an earlier tag push,
instead of coming from the release.

This should be really fixed now, and sorry for any confusion.