Handle really trivial case inside git-merge.

Using Linus' --trivial option, this handles really trivial case
inside git-merge itself, without using any strategy modules.

A 'really trivial case' is:

 - we are merging one branch into the current branch;
 - there is only one merge base between the branches;
 - there is no file-level merge required.

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

diff --git a/git-merge.sh b/git-merge.sh
index 29e86c6..d12a2a9 100755 (executable)
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -123,10 +123,30 @@ case "$#,$common" in
        dropsave
        exit 0
        ;;
-1,*)
+1,?*"$LF"?*)
        # We are not doing octopus and not fast forward.  Need a
        # real merge.
        ;;
+1,*)
+       # We are not doing octopus, not fast forward, and have only
+       # one common.  See if it is really trivial.
+       echo "Trying really trivial in-index merge..."
+       git-update-index --refresh 2>/dev/null
+       if git-read-tree --trivial -m -u $common $head "$1" &&
+          result_tree=$(git-write-tree)
+       then
+           echo "Wonderful."
+           result_commit=$(
+               echo "$merge_msg" |
+               git-commit-tree $result_tree -p HEAD -p "$1"
+           ) || exit
+           git-update-ref HEAD $result_commit $head
+           summary $result_commit
+           dropsave
+           exit 0
+       fi
+       echo "Nope."
+       ;;
 *)
        # An octopus.  If we can reach all the remote we are up to date.
        up_to_date=t