rebase -i: squash should retain the authorship of the _first_ commit

It was determined on the mailing list, that it makes more sense for a
"squash" to keep the author of the first commit as the author for the
result of the squash.

Make it so.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 2fa53fd..653393d 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -261,9 +261,9 @@
 		esac
 
 		failed=f
+		author_script=$(get_author_ident_from_commit HEAD)
 		output git reset --soft HEAD^
 		pick_one -n $sha1 || failed=t
-		author_script=$(get_author_ident_from_commit $sha1)
 		echo "$author_script" > "$DOTEST"/author-script
 		case $failed in
 		f)