http_build_query sometimes joins with "&amp;"

I've no idea why, but http_build_query sometimes builds the query with &amp; as the joing string, rather than the proper default of &.
See http://php.net/manual/en/function.http-build-query.php#102324.

This is happening to me :(

Thanks!
Merge pull request #491 from dan-james-deeson/patch-1

http_build_query sometimes joins with "&amp;"