This patch avoids several silly warnings, and fills $res->status_line with something useful 
in case your FTP server babbles some text message without a leading response code.
Seen from ftp.opensuse.org:
connect(3, {sa_family=AF_INET, sin_port=htons(21), sin_addr=inet_addr("195.135.221.134")}, 16) = 0
read(3, "This server is busy, please try again later or any of my mirrors: http://download.opensuse.org\n\n", 1024) = 96
Note the missing "500 " before "This".
Command line ftp clients handle this gracefully, so should we.

With this patch, LWP clients see a status_line of "500 This server is busy, ..."
2006-12-20, jw@suse.de

--- cpan/libnet/Net/FTP.pm.orig	2007-12-18 10:47:07.000000000 +0000
+++ cpan/libnet/Net/FTP.pm	2008-01-07 10:08:30.000000000 +0000
@@ -107,7 +107,7 @@ sub new {
 
   unless ($ftp->response() == CMD_OK) {
     $ftp->close();
-    $@ = $ftp->message;
+    $@ = $ftp->message || $@;	# keep $@ if no message. Happens when response did not start with a code.
     undef $ftp;
   }
 
@@ -1077,7 +1077,7 @@ sub command {
 
 sub response {
   my $ftp  = shift;
-  my $code = $ftp->SUPER::response();
+  my $code = $ftp->SUPER::response() || CMD_ERROR;	# assume error if undef
 
   delete ${*$ftp}{'net_ftp_pasv'}
     if ($code != CMD_MORE && $code != CMD_INFO);
@@ -1094,7 +1094,7 @@ sub parse_response {
 
   # Darn MS FTP server is a load of CRAP !!!!
   return ()
-    unless ${*$ftp}{'net_cmd_code'} + 0;
+    unless (${*$ftp}{'net_cmd_code'} || 0) + 0;
 
   (${*$ftp}{'net_cmd_code'}, 1);
 }
--- cpan/libnet/Net/Cmd.pm.orig	2007-12-18 10:47:07.000000000 +0000
+++ cpan/libnet/Net/Cmd.pm	2008-01-07 10:09:34.000000000 +0000
@@ -353,6 +353,7 @@ sub response {
     ($code, $more) = $cmd->parse_response($str);
     unless (defined $code) {
       $cmd->ungetline($str);
+      $@ = $str;	# $@ is used as a tunneling hack.
       last;
     }
 
@@ -363,6 +364,7 @@ sub response {
     last unless ($more);
   }
 
+  return undef unless defined $code;
   substr($code, 0, 1);
 }