Description:
------------
If a namespaced function is imported into the global scope it is
apparently not recognized by function_exists().


Test script:
---------------
<?php

namespace Foo {
    function bar() {
        echo 'I am there!';
    }
}

namespace {
    use function Foo\bar;

    var_dump(function_exists('bar'));
    bar();
}


Expected result:
----------------
bool(true)
I am there!


Actual result:
--------------
bool(false)
I am there!