[PATCH v2 0/5] show negatability of options in short help

Changes since v1: More fallout, still reduce size of final patch:
- Disable negation of "git subtree" options that don't support it.
- Adjust t7900 in contrib/subtree/t to the changed output.
- Adjust git-rev-parse.txt to the changed output.
- Disable negation of --help in t1502.
- Add negation tests to t1502.
- Deduplicate expected output in t1502.

  subtree: disallow --no-{help,quiet,debug,branch,message}
  t1502, docs: disallow --no-help
  t1502: move optionspec help output to a file
  t1502: test option negation
  parse-options: show negatability of options in short help

 Documentation/git-rev-parse.txt    |  10 +--
 contrib/subtree/git-subtree.sh     |  10 +--
 contrib/subtree/t/t7900-subtree.sh |   2 +-
 parse-options.c                    |  10 ++-
 t/t0040-parse-options.sh           |  44 +++++-----
 t/t1502-rev-parse-parseopt.sh      | 131 ++++++++++++-----------------
 t/t1502/.gitattributes             |   1 +
 t/t1502/optionspec-neg             |   8 ++
 t/t1502/optionspec-neg.help        |  11 +++
 t/t1502/optionspec.help            |  39 +++++++++
 10 files changed, 157 insertions(+), 109 deletions(-)
 create mode 100644 t/t1502/.gitattributes
 create mode 100644 t/t1502/optionspec-neg
 create mode 100644 t/t1502/optionspec-neg.help
 create mode 100755 t/t1502/optionspec.help

-- 2.41.0