git-am: minor cleanup

This moves the assignment to FIRSTLINE down so that we do not have
to have multiple copies.

Suggested by Linus.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -355,7 +355,6 @@ do
 			;;
 		esac
 	esac
-	FIRSTLINE=$(head -1 "$dotest/final-commit")
 
 	resume=
 	if test "$interactive" = t
@@ -376,7 +375,6 @@ do
 		[aA]*) action=yes interactive= ;;
 		[nN]*) action=skip ;;
 		[eE]*) git_editor "$dotest/final-commit"
-		       FIRSTLINE=$(head -1 "$dotest/final-commit")
 		       action=again ;;
 		[vV]*) action=again
 		       LESS=-S ${PAGER:-less} "$dotest/patch" ;;
@@ -386,6 +384,7 @@ do
 	else
 	    action=yes
 	fi
+	FIRSTLINE=$(head -1 "$dotest/final-commit")
 
 	if test $action = skip
 	then