src/Composer/DependencyResolver/RuleWatchNode.php
public function moveWatch($from, $to)
    {
        if ($this->watch1 == $from) {
            $this->watch1 = $to;
        } else {
            $this->watch2 = $to;
        }
    }
public function moveWatch($from, $to)
    {
        if ($this->watch1 == $from) {
            $this->watch1 = $to;
        } else {
            $this->watch2 = $to;
        }
    }
Moves a watch from one literal to another

@param int $from The previously watched literal
@param int $to   The literal to be watched now