Description:
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Wrong result if you are checking array for existing integer 0, when array has 
none integer values.. 

Test script:
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$array = array(1,2,3);
var_dump(in_array(0, $array)); 

$array = array(1,2,'some string not INT');
var_dump(in_array(0, $array)); 



Expected result:
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boolean false 

boolean false

Actual result:
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boolean false

boolean true