repo: refactor help output handling

Currently we have the behavior:
* `repo`: Equivalent to `repo help` -- only shows common subcommands
  (with short description), and then exits 0.
* `repo --help`: Shows repo's core options, lists all commands (no
  specific info), and then exits 0.

The first case is not behaving well:
* If you run `repo` without a specific subcommand, that's an error,
  so we should be exiting 1 instead.
* Showing only subcommands and no actual option summary makes it seem
  like repo itself doesn't take any options.  This confuses users.

Let's rework things a bit.  Now we have the behavior:
* `repo`: Shows repo's core options, lists all commands (no specific
  info), and then exits 1.
* `repo --help`: Shows repo's core options, shows common subcommands
  (with short description), and then exits 0.
* `repo --help-all`: Shows repo's core options, shows all subcommands
  (with short description), and then exits 0.

Basically we swap the behavior of `repo` and `repo --help`, and fix
the exit status when the subcommand is missing.

The addition of --help-all is mostly for the man pages.  We were
relying on `repo help --all` to generate the repo(1) man page, but
that too omitted the core repo options.  Now the man page includes
all the core repo options and provides a summary of all commands.

Change-Id: I1f99b99d5b8af2591f96a078d0647a3d76d6b0fc
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/312908
Reviewed-by: Xin Li <delphij@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/release/update-manpages b/release/update-manpages
index 3aeee206..f841f306 100755
--- a/release/update-manpages
+++ b/release/update-manpages
@@ -59,7 +59,7 @@ def main(argv):
   cmdlist.append(['help2man', '-N', '-n', 'repository management tool built on top of git',
     '-S', 'repo', '-m', 'Repo Manual', f'--version-string={version}',
     '-o', MANDIR.joinpath('repo.1'), TOPDIR.joinpath('repo'),
-    '-h', 'help --all'])
+    '-h', '--help-all'])
 
   with tempfile.TemporaryDirectory() as tempdir:
     repo_dir = Path(tempdir) / '.repo'