PriorityQueue capacity bug

[breath-co2]

test on ds 1.1.5, php 7.1.2

<?php
$queue = new \Ds\PriorityQueue();
$queue->push('first', 0);
for ($i = 0; $i < 10; $i ++) {
    $queue->pop();
    $queue->push('i-'.$i, $i);
    var_dump($queue->capacity());
}
$queue->push('end', 0);
print_r($queue);
var_dump($queue->capacity());
echo "done\n";

output:

int(4)
int(2)
int(1)
int(0)
int(0)
int(0)
int(0)
int(0)
int(0)
int(0)
Ds\PriorityQueue Object
(
    [0] => i-9
    [1] => end
)
int(0)
done

[rtheunissen]

Fixed and released as 1.1.8