patch 8.2.3952: first line not redrawn when adding lines to an empty buffer

Problem:    First line not redrawn when adding lines to an empty buffer.
Solution:   Adjust the argument to appended_lines(). (closes #9439,
            closes #9438)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 8595e8b..c57f332 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -3359,7 +3359,11 @@
 
 	did_undo = TRUE;
 	ml_append(lnum, theline, (colnr_T)0, FALSE);
-	appended_lines_mark(lnum + (empty ? 1 : 0), 1L);
+	if (empty)
+	    // there are no marks below the inserted lines
+	    appended_lines(lnum, 1L);
+	else
+	    appended_lines_mark(lnum, 1L);
 
 	vim_free(theline);
 	++lnum;