- Fred Machado posted about a weird FTP problem on the curl-users list and when

researching it, it turned out he got a 550 response back from a SIZE command
  and then I fell over the text in RFC3659 that says:

   The presence of the 550 error response to a SIZE command MUST NOT be taken
   by the client as an indication that the file cannot be transferred in the
   current MODE and TYPE.

  In other words: the change I did on September 30th 2008 and that has been
  included in the last two releases were a regression and a bad idea. We MUST
  NOT take a 550 response from SIZE as a hint that the file doesn't exist.

lib/ftp.c

@@ -2190,10 +2190,6 @@ static CURLcode ftp_state_size_resp(struct connectdata *conn,
   curl_off_t filesize;
   char *buf = data->state.buffer;
 
-  if((instate != FTP_STOR_SIZE) && (ftpcode == 550))
-    /* the file doesn't exist and we're not about to upload */
-    return CURLE_REMOTE_FILE_NOT_FOUND;
-
   /* get the size from the ascii string: */
   filesize = (ftpcode == 213)?curlx_strtoofft(buf+4, NULL, 0):-1;
 
@@ -3169,7 +3165,6 @@ static CURLcode ftp_done(struct connectdata *conn, CURLcode status,
   case CURLE_UPLOAD_FAILED:
   case CURLE_REMOTE_ACCESS_DENIED:
   case CURLE_FILESIZE_EXCEEDED:
-  case CURLE_REMOTE_FILE_NOT_FOUND:
     /* the connection stays alive fine even though this happened */
     /* fall-through */
   case CURLE_OK: /* doesn't affect the control connection's status */