The HTTP 1.1 spec which requires the last header be followed by two CRLF sequences.

Jep. From RFC 2616

 Request (section 5) and Response (section 6) messages use the generic
+ message format of RFC 822 [9] for transferring entities (the payload
+ of the message). Both types of message consist of a start-line, zero
+ or more header fields (also known as "headers"), an empty line (i.e.
+, a line with nothing preceding the CRLF) indicating the end of the h
+eader fields, and possibly a message-body.

        generic-message = start-line
                          *(message-header CRLF)
                          CRLF
                          [ message-body ]
        start-line      = Request-Line | Status-Line
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In short, the header is terminated by an empty line. Maybe I'm missing the point, but that's exactly what I get with:

print "$lastlineofheader\n\n;"