merge: allow merging into a yet-to-be-born branch.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/git-merge.sh b/git-merge.sh
index 25deb1e..dd4e83d 100755 (executable)
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -159,6 +159,24 @@ then
        shift
        head_arg="$1"
        shift
+elif ! git-rev-parse --verify HEAD 2>/dev/null
+then
+       # If the merged head is a valid one there is no reason to
+       # forbid "git merge" into a branch yet to be born.  We do
+       # the same for "git pull".
+       if test 1 -ne $#
+       then
+               echo >&2 "Can merge only exactly one commit into empty head"
+               exit 1
+       fi
+
+       rh=$(git rev-parse --verify "$1^0") ||
+               die "$1 - not something we can merge"
+
+       git-update-ref -m "initial pull" HEAD "$rh" "" &&
+       git-read-tree --reset -u HEAD
+       exit
+
 else
        # We are invoked directly as the first-class UI.
        head_arg=HEAD