Merge branch 'PHP-5.6' into PHP-7.0

* PHP-5.6:
  backport to 5.6 (we should not unset the default value)

Conflicts:
	Zend/zend_exceptions.c
	ext/standard/tests/serialize/bug69152.phpt

diff --cc ext/standard/tests/serialize/bug69152.phpt
index be3aa273ed1e54be7055ef4a43a0d3502e871cf9,4e741685ccd043ede839e898e3952cbaddafae59..b766c0afbdee95c83ed9c1640cf64b53f59d3ff1
--- 1/ext/standard/tests/serialize/bug69152.phpt
--- 2/ext/standard/tests/serialize/bug69152.phpt
+++ b/ext/standard/tests/serialize/bug69152.phpt
@@@ -9,8 -9,7 +9,7 @@@ $x->test()
  
  ?>
  --EXPECTF--
- Notice: Undefined property: Exception::$previous in %s on line %d
 -exception 'Exception' in %s:%d
 +Exception in %s:%d
  Stack trace:
  #0 {main}
  

diff --cc ext/standard/tests/serialize/bug69793.phpt
Simple merge

diff --cc ext/standard/tests/serialize/bug70963.phpt
index fc767712993f8262ed856d1927d648114afc727f,0000000000000000000000000000000000000000..93843c606bec2b9dc97b89d0cd7d46917bf4f687
mode 100644,000000..100644
--- 1/ext/standard/tests/serialize/bug70963.phpt
--- /dev/null
+++ b/ext/standard/tests/serialize/bug70963.phpt
@@@ -1,38 -1,0 +1,42 @@@
-   object(Exception)#%d (5) {
 +--TEST--
 +Bug #70963 (Unserialize shows UNKNOW in result)
 +--FILE--
 +<?php
 +var_dump(unserialize('a:2:{i:0;O:9:"exception":1:{s:16:"'."\0".'Exception'."\0".'trace";s:4:"test";}i:1;R:3;}'));
 +var_dump(unserialize('a:2:{i:0;O:9:"exception":1:{s:16:"'."\0".'Exception'."\0".'trace";s:4:"test";}i:1;r:3;}'));
 +?>
 +--EXPECTF--
 +array(1) {
 +  [0]=>
-     int(%d)
++  object(Exception)#%d (6) {
 +    ["message":protected]=>
 +    string(0) ""
 +    ["string":"Exception":private]=>
 +    string(0) ""
 +    ["code":protected]=>
 +    int(0)
 +    ["file":protected]=>
 +    string(%d) "%s"
 +    ["line":protected]=>
-   object(Exception)#%d (5) {
++    int(2)
++    ["previous":"Exception":private]=>
++    NULL
 +  }
 +}
 +array(1) {
 +  [0]=>
-     int(%d)
++  object(Exception)#%d (6) {
 +    ["message":protected]=>
 +    string(0) ""
 +    ["string":"Exception":private]=>
 +    string(0) ""
 +    ["code":protected]=>
 +    int(0)
 +    ["file":protected]=>
 +    string(%d) "%s"
 +    ["line":protected]=>
++    int(3)
++    ["previous":"Exception":private]=>
++    NULL
 +  }
 +}