Moved from github [https://github.com/ruby/ruby/pull/389]:
"As per http://tools.ietf.org/html/rfc4408#section-3.1.3, when a TXT or SPF record contains multiple strings, those strings should be concatenated without any delimiter. Resolv was taking the first string, which meant that valid data in a TXT record wouldn't be available. This change just concatenates the strings together."