libostree 2018.7

[Colin Walters <walters verbum org>]

https://github.com/ostreedev/ostree/releases/tag/v2018.7

I've said this before but the regular variety of contributors to libostree
makes me very happy - part of the reason I like working on Free Software
is collaborating with smart people around the world!  Thanks to all of you!

There's no one major feature in this release, but we have a variety
of improvements and bugfixes.

The addition of `min-free-space-size` in the previous release caused
issues with older libostree/flatpak interacting with it.  We now tolerate
both `min-free-space-size` and `min-free-space-percent` being set for
compatibility.
PR: #1685

The way libostree writes bootloader spec snippets has changed to
have the version number first, aiding sorting.  It turns out some BLS
implementations order via filename.  This is preparatory work for more
directly adopting the BLS in Fedora (and I for one will not miss grub2-mkconfig
and particularly os-prober)!

libostree became significantly smarter about handling "recommitting" content,
such as `ostree commit --tree=ref=foo -b bar`; it's now nearly free, and this
can be extended to very quickly "union" or merge different refs into a unified
whole.  See the discussion in:
PR: #1643

There are two fixes for staged deployments (still not the default), but
we're aiming to do that by default in rpm-ostree soon, and that's shaking
out some remaining issues (for example, the API didn't support overriding
kernel arguments correctly).

Another notable bugfix is for separate /var partition, which we regressed
in 2018.6 as part of working on Ignition integration.
PR: #1668

Thanks again to all contributors!

```
Alex Kiernan (2 PRs, 2 commits)
  boot: Use emergency.target, not emergency.service (#1665)
  switchroot: Move late /run/ostree-booted creation to ostree-system-generator (#1675)

Alex Kiernan (2 PRs, 2 commits)
  build: Use ostree_prepare_root_CPPFLAGS for ostree-prepare-root (#1670)
  switchroot: Fix typo in comment ENINVAL => EINVAL (#1676)

Colin Walters (9 PRs, 9 commits)
  sysroot: Reject attempts to pin the staged deployment (#1660)
  ci/flatpak: Fix to use built ostree version (#1662)
  deploy: Retain staged by default (#1672)
  deploy: Fix overriding kernel args for staged deployments (#1677)
  build-sys: Link with gpg-error directly (#1679)
  Update libglnx (#1680)
  ci: Mark insttests as not required (#1686)
  PR: #1652
    ci: Workaround getfedora.org/atomic_qcow2_latest being 404
    (and 1 commit from other author)
  PR: #1668
    tests/installed: Add var-mount.yml destructive test
    (and 2 commits from other authors)

Emmanuele Bassi (1 PR, 1 commit)
  Add a check for gpg-error via pkg-config (#1682)

Javier Martinez Canillas (2 PRs, 2 commits)
  ostree-grub-generator: sort BLS files by version instead of alphabetically (#1653)
  deploy: Change BootLoaderSpec filenames so they can be used for sorting (#1654)

Jonathan Lebon (2 PRs, 3 commits)
  PR: #1652
    tests/installed: Wait a bit more for http.server
    (and 1 commit from other author)
  PR: #1668
    tests/installed: Add NOTE when re-using RPMs
    switchroot: Fix regression for separately mounted /var
    (and 1 commit from other author)

Marcus Folkesson (2 PRs, 2 commits)
  ci: exclude 'lib' from libsoup configure option (#1661)
  build: add ostree-soup-* to build process when configured with avahi (#1666)

Matthew Leeds (2 PRs, 2 commits)
  man/ostree.repo-config: Document collection-id (#1646)
  create-usb: Tweak docs for --destination-repo (#1656)

Philip Withnall (1 PR, 1 commit)
  lib/repo-commit: Abort a transaction if preparing it fails (#1647)

Robert Fairley (2 PRs, 3 commits)
  tests: Run network retries test for many retries directly (#1673)
  PR: #1669
    ostree/pull: Add network-retries command line option
    tests: Move assert_fail function to tests/libtest.sh

Simon McVittie (2 PRs, 2 commits)
  avahi: Fail immediately if we can't talk to D-Bus or Avahi (#1639)
  OstreeRepoFinderConfig: Fix guint/gsize confusion (#1641)

Umang Jain (6 PRs, 9 commits)
  lib/repo: Minor fixes around min-free-space (#1663)
  Release 2018.7 (#1683)
  lib/repo: Allow min-free-space-size and -percent to co-exist (#1685)
  PR: #1602
    lib/repo: Cleanup current boot's staging dir min-free-space-* checks are hit
    lib/repo: cleanup_tmpdir should be executed after releasing lock file
  PR: #1614
    tests: Add tests for space checks during deltas codepath
    lib/repo: Enforce min-free-space-* size check for regfiles in deltas
  PR: #1671
    lib/repo-commit: Factor out min-free-space-size error reporting
    repo: Reword min-free-space-size option's error strings

William Manley (4 PRs, 7 commits)
  ostree repo commit: Speed up composing trees with `--tree=ref` (#1643)
  tests: Save corefiles back to tests/ directory if one exists (#1657)
  PR: #1645
    OstreeMutableTree: Document ostree_mutable_tree_ensure_dir
    OstreeMutableTree: Document each private member of `OstreeMutableTree`
    Add test for composing trees in different ways
  PR: #1655
    OstreeMutableTree: Invalidate parent contents checksum when metadata changes
    OstreeMutableTree: Refactor: Add `parent` pointer
```