git: openjdk/skara: A repository without refs but with objects is healthy

[duke]

Changeset: 6d6a0b69
Author:    Robin Westberg <rwestberg at openjdk.org>
Date:      2019-08-22 13:22:18 +0000
URL:       https://git.openjdk.java.net/skara/commit/6d6a0b69

A repository without refs but with objects is healthy

Reviewed-by: ehelin

! vcs/src/main/java/org/openjdk/skara/vcs/git/GitRepository.java
! vcs/src/test/java/org/openjdk/skara/vcs/RepositoryTests.java