[RFC_PATCHv4 0/7] Git submodule labels

This series introduces labels which you can attach to submodules like so:

    $ cat .gitmodules
    [submodule "gcc"]
        path = gcc
        url = git://...
        label = default
        label = devel
    [submodule "linux"]
        path = linux
        url = git://...
        label = default
        
    $ git submodule add --name emacs --label "editor" --label default git://...
    
    # If upstream has submodules properly labeled, you can make use of them:
    $ git config --add submodule.actionOnLabel "*default"
    $ git config --add submodule.actionOnLabel ":name"
    $ git config --add submodule.actionOnLabel "./by/path"
    # The prefix * denotes a label as found in .gitmodules
    # : goes before names 
    # path are prefixed ./ currently
    # both path and names need work

    # no --init necessary, partially initializes submodules (only those which
    # were specified by label, name or path)
    $ git submodule update
    
    # time passes, upstream may have added new submodules and we get them without
    # extra commands!
    $ git submodule update

    # The above configuration can be given to git clone directly via:
    $ git clone --init-submodule=*labelA ...
    
    # diff/status only apply to label-selected submodules
    git status

New since last round:
* Renamed to submodule.actionOnLabel as it is generic enough to be applicable
  for lots of commands (submodule update, status, diff, etc)
* Restructured the code to have a generic "Given these labels, would I
  want to operate on this submodule", which made the implementation for
  "submodule update" easier, as well as the new WIP patch for diff/status.

Any feedback would be welcome! Thanks, Stefan

An earlier version was posted at http://thread.gmane.org/gmane.comp.version-control.git/284612

This applies on top of origin/sb/submodule-init or can be found at https://github.com/stefanbeller/git/tree/submodule-groups-v4

Stefan Beller (7):
  git submodule: teach `add` to label submodules
  submodule-config: keep labels around
  submodule-config: add method to check for being labeled
  submodule init: redirect stdout to stderr
  submodule update: respect submodule.actionOnLabel
  clone: allow specification of submodules to be cloned
  WIP status/diff: respect submodule.actionOnLabel

 Documentation/git-clone.txt     |   6 +
 Documentation/git-submodule.txt |   5 +-
 builtin/clone.c                 |  40 +++++-
 builtin/submodule--helper.c     |  25 +++-
 git-submodule.sh                |  14 +-
 submodule-config.c              |  66 ++++++++-
 submodule-config.h              |   5 +
 submodule.c                     |  15 ++
 t/t7400-submodule-basic.sh      | 294 ++++++++++++++++++++++++++++++++++++++++
 9 files changed, 462 insertions(+), 8 deletions(-)