Description:
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var_export is exporting negative array key as maxint (64 bit). Example: -1 will be replaced with 18446744073709551615 

Test script:
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$aArray = array ( -1 => 'Hello', 1  => 'World');

$sExported = var_export($aArray,true);

echo $sExported;


Expected result:
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array ( -1 => 'Hello',1 => 'World')

Actual result:
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array ( 18446744073709551615 => 'Hello', 1 => 'World' )