updated for version 7.4.073
Problem:    Setting undolevels for one buffer changes undo in another.
Solution:   Make 'undolevels' a global-local option. (Christian Brabandt)
diff --git a/src/buffer.c b/src/buffer.c
index ddbcbc4..9dc7378 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1949,6 +1949,7 @@
     clear_string_option(&buf->b_p_qe);
 #endif
     buf->b_p_ar = -1;
+    buf->b_p_ul = NO_LOCAL_UNDOLEVEL;
 }
 
 /*