Merge branch 'jk/no-looking-at-dotgit-outside-repo'

Clean up fallouts from recent tightening of the set-up sequence, where Git barfs when repository information is accessed without first ensuring that it was started in a repository. * jk/no-looking-at-dotgit-outside-repo: test-read-cache: setup git dir has_sha1_file: don't bother if we are not in a repository