Fix crashes with unproper cleaning of repeated yield from

Zend/tests/generators/repeated_yield_from_with_immediate_release.phpt

@@ -0,0 +1,19 @@
+--TEST--
+A generator can be yielded from multiple times, testing immediate release of the yield from'ing generator
+--FILE--
+<?php
+
+function gen() {
+	yield 42;
+}
+function yield_from($gen) {
+	yield from $gen;
+}
+$gen = gen();
+var_dump(yield_from($gen)->current());
+var_dump(yield_from($gen)->current());
+
+?>
+--EXPECT--
+int(42)
+int(42)

Zend/tests/generators/yield_from_multi_tree_single_nodes.phpt

@@ -0,0 +1,328 @@
+--TEST--
+yield from on multiple trees needing merge, with intermediary nodes having only one child
+--FILE--
+<?php
+
+function from($levels) {
+    foreach (range(0, 2 << $levels) as $v) {
+        yield $v;
+    }
+}
+
+function gen($gen, $level) {
+    yield from (function() use ($gen) { yield from $gen; })();
+}
+
+foreach (range(0, 6) as $levels) {
+    print "$levels level".($levels == 1 ? "" : "s")."\n\n";
+
+    $all = array();
+    $all[] = $gens[0][0] = from($levels);
+
+    for ($level = 1; $level < $levels; $level++) {
+        for ($i = 0; $i < (1 << $level); $i++) {
+            $all[] = $gens[$level][$i] = gen($gens[$level-1][$i >> 1], $level);
+        }
+    }
+
+    while (1) {
+        foreach ($all as $gen) {
+            var_dump($gen->current());
+            $gen->next();
+            if (!$gen->valid()) {
+                break 2;
+            }
+        }
+    }
+
+    print "\n\n";
+}
+?>
+--EXPECT--
+0 levels
+
+int(0)
+int(1)
+int(2)
+
+
+1 level
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+
+
+2 levels
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+int(5)
+int(6)
+int(7)
+int(8)
+
+
+3 levels
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+int(5)
+int(6)
+int(7)
+int(8)
+int(9)
+int(10)
+int(11)
+int(12)
+int(13)
+int(14)
+int(15)
+int(16)
+
+
+4 levels
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+int(5)
+int(6)
+int(7)
+int(8)
+int(9)
+int(10)
+int(11)
+int(12)
+int(13)
+int(14)
+int(15)
+int(16)
+int(17)
+int(18)
+int(19)
+int(20)
+int(21)
+int(22)
+int(23)
+int(24)
+int(25)
+int(26)
+int(27)
+int(28)
+int(29)
+int(30)
+int(31)
+int(32)
+
+
+5 levels
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+int(5)
+int(6)
+int(7)
+int(8)
+int(9)
+int(10)
+int(11)
+int(12)
+int(13)
+int(14)
+int(15)
+int(16)
+int(17)
+int(18)
+int(19)
+int(20)
+int(21)
+int(22)
+int(23)
+int(24)
+int(25)
+int(26)
+int(27)
+int(28)
+int(29)
+int(30)
+int(31)
+int(32)
+int(33)
+int(34)
+int(35)
+int(36)
+int(37)
+int(38)
+int(39)
+int(40)
+int(41)
+int(42)
+int(43)
+int(44)
+int(45)
+int(46)
+int(47)
+int(48)
+int(49)
+int(50)
+int(51)
+int(52)
+int(53)
+int(54)
+int(55)
+int(56)
+int(57)
+int(58)
+int(59)
+int(60)
+int(61)
+int(62)
+int(63)
+int(64)
+
+
+6 levels
+
+int(0)
+int(1)
+int(2)
+int(3)
+int(4)
+int(5)
+int(6)
+int(7)
+int(8)
+int(9)
+int(10)
+int(11)
+int(12)
+int(13)
+int(14)
+int(15)
+int(16)
+int(17)
+int(18)
+int(19)
+int(20)
+int(21)
+int(22)
+int(23)
+int(24)
+int(25)
+int(26)
+int(27)
+int(28)
+int(29)
+int(30)
+int(31)
+int(32)
+int(33)
+int(34)
+int(35)
+int(36)
+int(37)
+int(38)
+int(39)
+int(40)
+int(41)
+int(42)
+int(43)
+int(44)
+int(45)
+int(46)
+int(47)
+int(48)
+int(49)
+int(50)
+int(51)
+int(52)
+int(53)
+int(54)
+int(55)
+int(56)
+int(57)
+int(58)
+int(59)
+int(60)
+int(61)
+int(62)
+int(63)
+int(64)
+int(65)
+int(66)
+int(67)
+int(68)
+int(69)
+int(70)
+int(71)
+int(72)
+int(73)
+int(74)
+int(75)
+int(76)
+int(77)
+int(78)
+int(79)
+int(80)
+int(81)
+int(82)
+int(83)
+int(84)
+int(85)
+int(86)
+int(87)
+int(88)
+int(89)
+int(90)
+int(91)
+int(92)
+int(93)
+int(94)
+int(95)
+int(96)
+int(97)
+int(98)
+int(99)
+int(100)
+int(101)
+int(102)
+int(103)
+int(104)
+int(105)
+int(106)
+int(107)
+int(108)
+int(109)
+int(110)
+int(111)
+int(112)
+int(113)
+int(114)
+int(115)
+int(116)
+int(117)
+int(118)
+int(119)
+int(120)
+int(121)
+int(122)
+int(123)
+int(124)
+int(125)
+int(126)
+int(127)
+int(128)