src/Composer/Installer.php
private function moveUninstallsToFront(array $operations)
    {
        $uninstOps = array();
        foreach ($operations as $idx => $op) {
            if ($op instanceof UninstallOperation) {
                $uninstOps[] = $op;
                unset($operations[$idx]);
            }
        }

        return array_merge($uninstOps, $operations);
    }
private function moveUninstallsToFront(array $operations)
    {
        $uninstOps = array();
        foreach ($operations as $idx => $op) {
            if ($op instanceof UninstallOperation) {
                $uninstOps[] = $op;
                unset($operations[$idx]);
            }
        }

        return array_merge($uninstOps, $operations);
    }
Removals of packages should be executed before installations in
case two packages resolve to the same path (due to custom installers)

@param  OperationInterface[] $operations
@return OperationInterface[] reordered operation list