Merge branch 'dl/octopus-graph-bug' into next

"git log --graph" for an octopus merge is sometimes colored
incorrectly, which is demonstrated and documented but not yet
fixed.

* dl/octopus-graph-bug:
  t4214: demonstrate octopus graph coloring failure
  t4214: explicitly list tags in log
  t4214: generate expect in their own test cases
  t4214: use test_merge
  test-lib: let test_merge() perform octopus merges

diff --cc t/test-lib-functions.sh
Simple merge