prepend: fix ancestors order

* class.c (rb_mod_ancestors): fix ancestors order.
  [ruby-core:45919][Bug #6658] [ruby-dev:45861][Bug #6659]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36241 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 2 deletions

diff --git a/class.c b/class.c
index a642ff0029..9ff56f8563 100644
--- a/class.c
+++ b/class.c
@@ -838,11 +838,22 @@ VALUE
 rb_mod_ancestors(VALUE mod)
 {
     VALUE p, ary = rb_ary_new();
+    VALUE origin = RCLASS_ORIGIN(mod);
 
-    for (p = mod; p; p = RCLASS_SUPER(p)) {
+    p = mod;
+    if (origin == mod) {
+	origin = 0;
+    }
+    else {
+	p = RCLASS_SUPER(p);
+    }
+    for (; p; p = RCLASS_SUPER(p)) {
 	if (FL_TEST(p, FL_SINGLETON))
 	    continue;
-	if (BUILTIN_TYPE(p) == T_ICLASS) {
+	if (p == origin) {
+	    rb_ary_push(ary, mod);
+	}
+	else if (BUILTIN_TYPE(p) == T_ICLASS) {
 	    rb_ary_push(ary, RBASIC(p)->klass);
 	}
 	else {