updated for version 7.4.285
Problem:    When 'relativenumber' is set and deleting lines or undoing that,
            line numbers are not always updated. (Robert Arkwright)
Solution:   (Christian Brabandt)
diff --git a/src/misc1.c b/src/misc1.c
index 31a9c64..88ebd8d 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -3125,6 +3125,9 @@
 	    if (hasAnyFolding(wp))
 		set_topline(wp, wp->w_topline);
 #endif
+	    /* relative numbering may require updating more */
+	    if (wp->w_p_rnu)
+		redraw_win_later(wp, SOME_VALID);
 	}
     }