Fix default pull not to do an unintended Octopus.

The refspecs specified in the .git/remotes/<remote> on the "Pull: "
lines are for fetching multiple heads in one go, but most of the time
making an Octopus out of them is not what is wanted.  Make git-fetch
leave the marker in .git/FETCH_HEAD file so that later stages can
tell which heads are for merging and which are not.

Tom Prince made me realize how stupid the original behaviour was.

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

git-fetch.sh

@@ -54,6 +54,10 @@ append_fetch_head () {
     remote_name_="$3"
     remote_nick_="$4"
     local_name_="$5"
+    case "$6" in
+    t) not_for_merge_='not-for-merge' ;;
+    '') not_for_merge_= ;;
+    esac
 
     # remote-nick is the URL given on the command line (or a shorthand)
     # remote-name is the $GIT_DIR relative refs/ path we computed
@@ -78,10 +82,11 @@ append_fetch_head () {
     if git-cat-file commit "$head_" >/dev/null 2>&1
     then
 	headc_=$(git-rev-parse --verify "$head_^0") || exit
-	echo "$headc_	$note_" >>$GIT_DIR/FETCH_HEAD
+	echo "$headc_	$not_for_merge_	$note_" >>$GIT_DIR/FETCH_HEAD
 	echo >&2 "* committish: $head_"
 	echo >&2 "  $note_"
     else
+	echo "$head_	not-for-merge	$note_" >>$GIT_DIR/FETCH_HEAD
 	echo >&2 "* non-commit: $head_"
 	echo >&2 "  $note_"
     fi
@@ -157,6 +162,13 @@ do
 
     # These are relative path from $GIT_DIR, typically starting at refs/
     # but may be HEAD
+    if expr "$ref" : '\.' >/dev/null
+    then
+	not_for_merge=t
+	ref=$(expr "$ref" : '\.\(.*\)')
+    else
+	not_for_merge=
+    fi
     if expr "$ref" : '\+' >/dev/null
     then
 	single_force=t
@@ -216,7 +228,8 @@ do
 	continue ;;
     esac
 
-    append_fetch_head "$head" "$remote" "$remote_name" "$remote_nick" "$local_name"
+    append_fetch_head "$head" "$remote" \
+    	"$remote_name" "$remote_nick" "$local_name" "$not_for_merge"
 
 done
 
@@ -241,16 +254,27 @@ http://* | https://* | rsync://* )
 	    case "$ref" in
 	    +$remote_name:*)
 		single_force=t
+		not_for_merge=
+		found="$ref"
+		break ;;
+	    .+$remote_name:*)
+		single_force=t
+		not_for_merge=t
+		found="$ref"
+		break ;;
+	    .$remote_name:*)
+	        not_for_merge=t
 		found="$ref"
 		break ;;
 	    $remote_name:*)
+	    	not_for_merge=
 		found="$ref"
 		break ;;
 	    esac
 	done
-
 	local_name=$(expr "$found" : '[^:]*:\(.*\)')
-	append_fetch_head "$sha1" "$remote" "$remote_name" "$remote_nick" "$local_name"
+	append_fetch_head "$sha1" "$remote" \
+		"$remote_name" "$remote_nick" "$local_name" "$not_for_merge"
     done || exit
     ;;
 esac

git-fmt-merge-msg.perl

@@ -31,6 +31,8 @@ sub andjoin {
 	my ($bname, $tname, $gname, $src);
 	chomp;
 	s/^[0-9a-f]*	//;
+	next if (/^not-for-merge/);
+	s/^	//;
 	if (s/ of (.*)$//) {
 		$src = $1;
 	} else {
@@ -86,7 +88,7 @@ sub andjoin {
 			    $src{$src}{GENERIC});
 	my $this = join(', ', @this);
 	if ($src ne '.') {
-		$this .= " from $src";
+		$this .= " of $src";
 	}
 	push @msg, $this;
 }

git-parse-remote.sh

@@ -65,8 +65,11 @@ get_remote_default_refs_for_push () {
 	esac
 }
 
-# Subroutine to canonicalize remote:local notation
+# Subroutine to canonicalize remote:local notation.
 canon_refs_list_for_fetch () {
+	# Leave only the first one alone; add prefix . to the rest
+	# to prevent the secondary branches to be merged by default.
+	dot_prefix=
 	for ref
 	do
 		force=
@@ -91,7 +94,8 @@ canon_refs_list_for_fetch () {
 		heads/* | tags/* ) local="refs/$local" ;;
 		*) local="refs/heads/$local" ;;
 		esac
-		echo "${force}${remote}:${local}"
+		echo "${dot_prefix}${force}${remote}:${local}"
+		dot_prefix=.
 	done
 }
 
@@ -107,6 +111,9 @@ get_remote_default_refs_for_fetch () {
 		echo "refs/heads/${remote_branch}:refs/heads/$1"
 		;;
 	remotes)
+		# This prefixes the second and later default refspecs
+		# with a '.', to signal git-fetch to mark them
+		# not-for-merge.
 		canon_refs_list_for_fetch $(sed -ne '/^Pull: */{
 						s///p
 					}' "$GIT_DIR/remotes/$1")

git-pull.sh

@@ -24,7 +24,9 @@ then
 		die "You need to first update your working tree."
 fi
 
-merge_head=$(sed -e 's/	.*//' "$GIT_DIR"/FETCH_HEAD | tr '\012' ' ')
+merge_head=$(sed -e '/	not-for-merge	/d' \
+	-e 's/	.*//' "$GIT_DIR"/FETCH_HEAD | \
+	tr '\012' ' ')
 
 case "$merge_head" in
 '')