Description:
------------
This happens when method of a sub-class introduce new, optional parameters which are needed for an interface implementation. If a trait is source for the implementation of that method then a fatal error is triggered:
 Fatal error: Declaration of Base::push() must be compatible with I::push

Bug #60153 might be related as it considers opposite situation.

I've checked this with:
5.4.1
5.4.7
5.5-dev (snap 201209280930)

Test script:
---------------
<?php
error_reporting(E_ALL);

interface I
{
    public function push($val, $scope = null);
}

trait T
{
    public function push($val, $scope = null){}
}

class Base
{
    public function push($val){}
}

class Sub extends Base
{
    use T;
}

$SubReflection = new ReflectionClass('Sub');
// this shows correct push() method, compatible with 'I' interface:
echo $SubReflection->getMethod('push');

// however adding 'implements I' triggers fatal error:
class SubImplements extends Base implements I
{
    use T;
}

Expected result:
----------------
No errors (interface is implemented properly)

Actual result:
--------------
Fatal error: Declaration of Base::push() must be compatible with I::push($val, $scope = NULL)