MergeQuery returning wrong result

[dmaicher]

Issue summary

The MergeQuery modifier returns wrong result since update from 4.1.1 to 4.2.0.

System informations

Information	Description
League\Uri version	4.2.0
PHP version	5.6.22
OS Platform	Debian 8

Standalone code, or other way to reproduce the problem

use League\Uri\Modifiers\MergeQuery;
use League\Uri\Schemes\Http;

class UrlQueryStringAppender
{
    /**
     * @param string $url
     * @param array  $queryParams
     *
     * @return string
     */
    public function appendToUrl($url, array $queryParams)
    {
        if (count($queryParams) === 0) {
            return $url;
        }

        $uri = Http::createFromString($url);
        $modifier = new MergeQuery(http_build_query($queryParams));

        return $modifier->__invoke($uri)->__toString();
    }
}

(new UrlQueryStringAppender())->appendToUrl('http://localhost?foo=foo&bar=%26foo#bar', [
    'foo' => '%bar'
])

Expected result

Should return http://localhost?foo=%25bar&bar=%26foo#bar

Actual result

Now returns http://localhost?foo=%BAr&bar=%26foo#bar

Problem appears since I updated from 4.1.1 to 4.2.0.

[nyamsprod]

@dmaicher the bug is fixed on the master branch can you confirm it so I close this issue on the next release.

[dmaicher]

My test cases pass now 👍

[nyamsprod]

version 4.2.1 is out which fixes this issue