Merge pull request libgit2#4756 from pks-t/pks/v0.27.4

Release v0.27.4

Merge pull request libgit2#4757 from pks-t/pks/v0.26.6

Release v0.26.6

Merge pull request libgit2#4717 from pks-t/pks/v0.27.3

Release v0.27.3

Merge pull request libgit2#4718 from pks-t/pks/v0.26.5

Release v0.26.5

Merge pull request libgit2#4632 from pks-t/pks/v0.27.1

Bugfix release v0.27.2

Merge pull request libgit2#4666 from pks-t/pks/v0.26.4

Release v0.26.4

Merge pull request libgit2#4659 from libgit2/ethomson/submodule-0_27

Backport fixes for CVE 2018-11235

Merge pull request libgit2#4594 from pks-t/pks/mempack-assert

odb: fix writing to fake write streams

Merge pull request libgit2#4563 from libgit2/ethomson/ssh-unescape

Refactor `gitno_extract_url_parts`

Merge pull request libgit2#4475 from pks-t/pks/v0.26.1-backports

v0.26.3 backports