Merge branch 'ph/submodule-rebase' (early part)

* 'ph/submodule-rebase' (early part):
  Rename submodule.<name>.rebase to submodule.<name>.update
  git-submodule: add support for --rebase.

Conflicts:
	Documentation/git-submodule.txt
	git-submodule.sh

diff --cc Documentation/git-submodule.txt
index 14256c695b3817014be8ba4f45a62a2cd588939c,f993469dc642d6fc84a07826c3782b8e22e3e223..cd8e861ce4ae33b25928a16aa213933d2a38a155
--- 1/Documentation/git-submodule.txt
--- 2/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@@ -9,12 -9,10 +9,12 @@@ git-submodule - Initialize, update or i
  SYNOPSIS
  --------
  [verse]
 -'git submodule' [--quiet] add [-b branch] [--] <repository> <path>
 +'git submodule' [--quiet] add [-b branch]
 +            [--reference <repository>] [--] <repository> <path>
  'git submodule' [--quiet] status [--cached] [--] [<path>...]
  'git submodule' [--quiet] init [--] [<path>...]
- 'git submodule' [--quiet] update [--init] [-N|--no-fetch]
 -'git submodule' [--quiet] update [--init] [-N|--no-fetch] [--rebase] [--] [<path>...]
++'git submodule' [--quiet] update [--init] [-N|--no-fetch] [--rebase]
 +            [--reference <repository>] [--] [<path>...]
  'git submodule' [--quiet] summary [--summary-limit <n>] [commit] [--] [<path>...]
  'git submodule' [--quiet] foreach <command>
  'git submodule' [--quiet] sync [--] [<path>...]
@@@ -179,14 -178,15 +180,23 @@@ OPTION
        This option is only valid for the update command.
        Don't fetch new objects from the remote site.
  
+ --rebase::
+       This option is only valid for the update command.
+       Rebase the current branch onto the commit recorded in the
+       superproject. If this option is given, the submodule's HEAD will not
+       be detached. If a a merge failure prevents this process, you will have
+       to resolve these failures with linkgit:git-rebase[1].
+       If the key `submodule.$name.update` is set to `rebase`, this option is
+       implicit.
+ 
 +--reference <repository>::
 +      This option is only valid for add and update commands.  These
 +      commands sometimes need to clone a remote repository. In this case,
 +      this option will be passed to the linkgit:git-clone[1] command.
 ++
 +*NOTE*: Do *not* use this option unless you have read the note
 +for linkgit:git-clone[1]'s --reference and --shared options carefully.
 +
  <path>...::
        Paths to submodule(s). When specified this will restrict the command
        to only operate on the submodules found at the specified paths.

diff --cc git-submodule.sh
index ab1ed02a663b7e6252fe33f5224cb9653bcd50f2,f384c6b2b4953110ab0f892aabdbb826ac2263da..19a3a840fdc7eed4994741e13306b71a3ffd2ada
--- 1/git-submodule.sh
--- 2/git-submodule.sh
+++ b/git-submodule.sh
@@@ -15,9 -15,9 +15,10 @@@ require_work_tre
  command=
  branch=
  quiet=
 +reference=
  cached=
  nofetch=
+ update=
  
  #
  # print stuff on stdout unless -q was specified
@@@ -337,15 -327,10 +343,19 @@@ cmd_update(
                        shift
                        nofetch=1
                        ;;
+               -r|--rebase)
+                       shift
+                       update="rebase"
+                       ;;
 +              --reference)
 +                      case "$2" in '') usage ;; esac
 +                      reference="--reference=$2"
 +                      shift 2
 +                      ;;
 +              --reference=*)
 +                      reference="$1"
 +                      shift
 +                      ;;
                --)
                        shift
                        break