zendframework/zf2 — pull request #4224 by Steffen185 (2013-04-14 09:35:45+00:00)
Title: Mail\Headers.php: Adjust regex for field name to RFC 5322

According to RFC 5322 (http://tools.ietf.org/html/rfc5322#section-2.2), a field name may contain "printable US-ASCII characters (i.e., characters that have values between 33 and 126, inclusive), except colon".