Bugfix: Long username-password-combinations will not result in an authentication error anymore.

If a username-password-combination is too long, perl's encode_base64 method will break the encoded string (stored in $auth) up into multiple lines of no more than 74 chars[0]. This breaks HTTP's authorization, since long values must not be folded into multiple lines[1].

[0] http://perldoc.perl.org/MIME/Base64.html
[1] http://tools.ietf.org/html/rfc7230#section-3.2.4