fixes #5253

Issue appears to be valid.

Specification doesn't state that spaces must exist after field-name only that it's preferred they do.
http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html

" Each header field consists of a name followed by a colon (":") and the field value. Field names are case-insensitive. The field value MAY be preceded by any amount of LWS, though a single SP is preferred. "

Perhaps I've misunderstood this, anyways it seems like better form to "fix" improper headers if we can.