[RFC PATCH v5 0/3] push: add support for pushing to remote groups

This RFC series adds support for `git push` to accept a remote group name (as configured via `remotes.<name>` in config) in addition to a single remote name, mirroring the behaviour that `git fetch` has supported for some time.

A user with multiple remotes configured as a group can now do:

    git push all-remotes

instead of pushing to each remote individually, in the same way that:

    git fetch all-remotes

already works.

The series is split into three patches:

  - Patch 1 fix sign-compare warnings in push_cas_option
  - Patch 2 moves `get_remote_group`, `add_remote_or_group`, and the
    `remote_group_data` struct out of builtin/fetch.c and into
    remote.c/remote.h, making them part of the public remote API.

  - Patch 2 extends builtin/push.c to use the newly public
    `add_remote_or_group()` to resolve the repository argument as
    either a single remote or a group, and pushes to each member of
    the group in turn.

Changes in v6:
- fix docs formating 

Range-diff v5 -> v6:

1:  e01126890c = 1:  e01126890c remote: fix sign-compare warnings in push_cas_option
2:  adbce652e6 = 2:  adbce652e6 remote: move remote group resolution to remote.c
3:  a8d5f4b7bd ! 3:  62a4499be6 push: support pushing to a remote group
    @@ Documentation/git-push.adoc: further recursion will occur. In this case, `only`
     +	...
     +	git push <options> rN <args>
     +
    -+where r1, r2, ..., rN are the members of `all-remotes`.  No special
    ++where `r1`, `r2`, ..., `rN` are the members of `all-remotes`.  No special
     +behaviour is added or removed — the group is purely a shorthand for
     +running the same push command against each member remote individually.
     +
    @@ Documentation/git-push.adoc: further recursion will occur. In this case, `only`
     +any member push fails.
     +
     +This means the user is responsible for ensuring that the sequence of
    -+individual pushes makes sense. If `git push r1`` would fail for a given
    ++individual pushes makes sense. If `git push r1` would fail for a given
     +set of options and arguments, then `git push all-remotes` will fail in
    -+the same way when it reaches r1. The group push does not do anything
    ++the same way when it reaches `r1`. The group push does not do anything
     +special to make a failing individual push succeed.
     +
      OUTPUT

Usman Akinyemi (3):
  remote: fix sign-compare warnings in push_cas_option
  remote: move remote group resolution to remote.c
  push: support pushing to a remote group

 Documentation/git-push.adoc |  80 ++++++++++--
 builtin/fetch.c             |  42 ------
 builtin/push.c              | 251 +++++++++++++++++++++++++++++++-----
 remote.c                    |  37 ++++++
 remote.h                    |  16 ++-
 t/meson.build               |   1 +
 t/t5566-push-group.sh       | 160 +++++++++++++++++++++++
 7 files changed, 502 insertions(+), 85 deletions(-)
 create mode 100755 t/t5566-push-group.sh