Fixed parsing of absolute URIs with empty path (ticket #2079). When the request line contains request-target in the absolute-URI form, it can contain path-empty instead of a single slash (see RFC 7230, RFC 3986). Previously, the ngx_http_parse_request_line() function only accepted empty path when there was no query string. With this change, non-empty query is also correctly handled. That is, request line "GET http://example.com?foo HTTP/1.1" is accepted and results in $uri "/" and $args "foo". Note that $request_uri remains "?foo", similarly to how spaces in URIs are handled. Providing "/?foo", similarly to how "/" is provided for "GET http://example.com HTTP/1.1", requires allocation.