Re: [PATCH v3] help: make option --help open man pages only for Git commands

If option --help is passed to a Git command, we try to open
the man page of that command.  However, we do it even for commands
we don't know.  Make sure it is a Git command by using "help_unknown_cmd"
which is even able to assume a command if the user made a typo.

This breaks "git <concept> --help" while "git help <concept>" still works.

As "<cmd> --help" will internally be turned into "help <cmd>",
introduce the hidden option "--swapped" in order to know which
version has been called.

Signed-off-by: Ralf Thielow <redacted>
---
Thanks, all, for the help!

Changes since v2:
- don't check for common guides as the list is very incomplete
- only check for git commands when called via <cmd> --help (introduce
  option --swapped for that), as suggested by Junio
- change test case to check for --help being passed to a concept
  used as a git command

 builtin/help.c  | 30 +++++++++++++++++++++++-------
 git.c           | 15 ++++++++++++++-
 t/t0012-help.sh | 15 +++++++++++++++
 3 files changed, 52 insertions(+), 8 deletions(-)
 create mode 100755 t/t0012-help.sh

diff --git a/builtin/help.c b/builtin/help.c
index 8848013..76f07c7 100644
--- a/builtin/help.c
+++ b/builtin/help.c

@@ -37,7 +37,9 @@ static int show_all = 0;
 static int show_guides = 0;
 static unsigned int colopts;
 static enum help_format help_format = HELP_FORMAT_NONE;
+static int swapped = 0;
 static struct option builtin_help_options[] = {
+	OPT_BOOL('s', "swapped", &swapped, "mark as being called by <cmd> --help"),