patch 7.4.2137
Problem:    Using function() with a name will find another function when it is
            redefined.
Solution:   Add funcref().  Refer to lambda using a partial.  Fix several
            reference counting issues.
diff --git a/src/regexp.c b/src/regexp.c
index 6b23cfb..6a685e3 100644
--- a/src/regexp.c
+++ b/src/regexp.c
@@ -7499,7 +7499,7 @@
 		    {
 			partial_T   *partial = expr->vval.v_partial;
 
-			s = partial->pt_name;
+			s = partial_name(partial);
 			call_func(s, (int)STRLEN(s), &rettv,
 					1, argv, fill_submatch_list,
 					  0L, 0L, &dummy, TRUE, partial, NULL);