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

Update "git diff --no-index" codepath not to try to peek into .git/ directory that happens to be under the current directory, when we know we are operating outside any repository. * jk/no-looking-at-dotgit-outside-repo: diff: handle sha1 abbreviations outside of repository diff_aligned_abbrev: use "struct oid" diff_unique_abbrev: rename to diff_aligned_abbrev find_unique_abbrev: use 4-buffer ring test-*-cache-tree: setup git dir read info/{attributes,exclude} only when in repository