Merge branch 'jk/diff-highlight-graph-fix'

"diff-highlight" filter (in contrib/) learned to undertand "git log --graph" output better. * jk/diff-highlight-graph-fix: diff-highlight: detect --graph by indent diff-highlight: use flush() helper consistently diff-highlight: test graphs with --color diff-highlight: test interleaved parallel lines of history diff-highlight: prefer "echo" to "cat" in tests diff-highlight: use test_tick in graph test diff-highlight: correct test graph diagram