[PATCH] allow merging any committish

Although "git-merge" is advertised as the end-user level command
(instead of being a "git-pull" backend), it was not prepared to
take tag objects that point at commits and barfed when fed one.
Sanitize the input while we validate them, for which we already
have a loop.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-merge.sh

@@ -97,11 +97,14 @@ head=$(git-rev-parse --verify "$1"^0) || usage
 shift
 
 # All the rest are remote heads
+remoteheads=
 for remote
 do
-	git-rev-parse --verify "$remote"^0 >/dev/null ||
+	remotehead=$(git-rev-parse --verify "$remote"^0) ||
 	    die "$remote - not something we can merge"
+	remoteheads="${remoteheads}$remotehead "
 done
+set x $remoteheads ; shift
 
 case "$#" in
 1)