Description:
------------
It appears that unserialize() does not unserialize 
numerics that are "non-finite", such as NAN and INF. 
Instead, it simply fails and returns (bool)false. 
 
If a NAN value is encountered anywhere during an 
unserialize() (for example, in an array or an object), the 
entire operation fails and unserialize will return false. 

Reproduce code:
---------------
$testNan = (float)NAN;
var_dump($testNan); //outputs float(NAN)
$testNan2 = unserialize(serialize($testNan));
var_dump($testNan2); //outputs bool(false)

$testInf = (float)INF;
var_dump($testInf); //outputs float(INF)
$testInf2 = unserialize(serialize($testInf));
var_dump($testInf2); //outputs bool(false)

Expected result:
----------------
float(NAN) 
float(NAN) 
float(INF) 
float(INF) 

Actual result:
--------------
float(NAN) 
bool(false) 
float(INF) 
bool(false)