Merge branch 'dm/unbash-subtree'

It turns out that git-subtree script does not have to be run with
bash.

* dm/unbash-subtree:
contrib/git-subtree: Use /bin/sh interpreter instead of /bin/bash

diff --combined contrib/subtree/git-subtree.sh
index 10daa8b0eb3352305347354d09ef443993af7809,57013763ec5abc95f414ce919907dc074d9a99b5..51ae932e5edc54db32fca93e8f6f8aca1bea32f4
--- 1/contrib/subtree/git-subtree.sh
--- 2/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@@ -1,4 -1,4 +1,4 @@@
- #!/bin/bash
+ #!/bin/sh
  #
  # git-subtree.sh: split/join git repositories in subdirectories of this one
  #
@@@ -715,8 -715,7 +715,8 @@@ cmd_push(
            repository=$1
            refspec=$2
            echo "git push using: " $repository $refspec
 -          git push $repository $(git subtree split --prefix=$prefix):refs/heads/$refspec
 +          localrev=$(git subtree split --prefix="$prefix") || die
 +          git push $repository $localrev:refs/heads/$refspec
        else
            die "'$dir' must already exist. Try 'git subtree add'."
        fi