Merge branch 'dl/test-cleanup'

Merge branch 'dl/test-cleanup'

Test cleanup.

* dl/test-cleanup: (26 commits)
  t7700: stop losing return codes of git commands
  t7700: make references to SHA-1 generic
  t7700: replace egrep with grep
  t7700: consolidate code into test_has_duplicate_object()
  t7700: consolidate code into test_no_missing_in_packs()
  t7700: s/test -f/test_path_is_file/
  t7700: move keywords onto their own line
  t7700: remove spaces after redirect operators
  t7700: drop redirections to /dev/null
  t7501: stop losing return codes of git commands
  t7501: remove spaces after redirect operators
  t5703: stop losing return codes of git commands
  t5703: simplify one-time-sed generation logic
  t5317: use ! grep to check for no matching lines
  t5317: stop losing return codes of git commands
  t4138: stop losing return codes of git commands
  t4015: use test_write_lines()
  t4015: stop losing return codes of git commands
  t3600: comment on inducing SIGPIPE in `git rm`
  t3600: stop losing return codes of git commands
  ...