patch-src::fix_uninitialized_value_header_field_name-3.4.0.patch by Victor Ustugov <corvax+spamassassin@mta.org.ua>

diff -urN lib.orig/Mail/SpamAssassin/Message/Node.pm lib/Mail/SpamAssassin/Message/Node.pm
--- lib.orig/Mail/SpamAssassin/Message/Node.pm	2014-03-10 19:48:45.000000000 +0200
+++ lib/Mail/SpamAssassin/Message/Node.pm	2014-04-21 21:12:09.000000000 +0300
@@ -645,12 +645,14 @@
   $header_field_body =~ s/\015?\012//gs;
 
   # Bug 6945: some header fields must not be processed for MIME encoding
+if ($header_field_name) {
   if ($header_field_name =~
        /^ (?: (?: Received | (?:Resent-)? (?: Message-ID | Date ) |
                   MIME-Version | References | In-Reply-To ) \z
             | (?: List- | Content- ) ) /xsi ) {
     return $header_field_body;
   }
+}
 
   # multiple encoded sections must ignore the interim whitespace.
   # to avoid possible FPs with (\s+(?==\?))?, look for the whole RE