Remove workaround code for bug539

We fixed bug 539 (where directories would say "503" but send data
anyway) back in 0.2.0.16-alpha/0.1.2.19.  Because most directory
versions were affected, we added workaround to make sure that we
examined the contents of 503-replies to make sure there wasn't any
data for them to find.  But now that such routers are nonexistent,
we can remove this code.  (Even if somebody fired up an 0.1.2.19
directory cache today, it would still be fine to ignore data in its
erroneous 503 replies.)

changes/bug539_removal

@@ -0,0 +1,6 @@
+  o Removed code
+    - Removed workaround code to handle directory responses from
+      servers that had bug 539 (they would send HTTP status 503
+      responses _and_ send a body too).  Since only server versions
+      before 0.2.0.16-alpha/0.1.2.19 were affected, there is no longer
+      reason to keep the workaround in place.

src/or/directory.c

@@ -1539,26 +1539,19 @@ connection_dir_client_reached_eof(dir_connection_t *conn)
   (void) skewed; /* skewed isn't used yet. */
 
   if (status_code == 503) {
-    if (body_len < 16) {
-      routerstatus_t *rs;
-      trusted_dir_server_t *ds;
-      log_info(LD_DIR,"Received http status code %d (%s) from server "
-               "'%s:%d'. I'll try again soon.",
-               status_code, escaped(reason), conn->_base.address,
-               conn->_base.port);
-      if ((rs = router_get_consensus_status_by_id(conn->identity_digest)))
-        rs->last_dir_503_at = now;
-      if ((ds = router_get_trusteddirserver_by_digest(conn->identity_digest)))
-        ds->fake_status.last_dir_503_at = now;
+    routerstatus_t *rs;
+    trusted_dir_server_t *ds;
+    log_info(LD_DIR,"Received http status code %d (%s) from server "
+             "'%s:%d'. I'll try again soon.",
+             status_code, escaped(reason), conn->_base.address,
+             conn->_base.port);
+    if ((rs = router_get_consensus_status_by_id(conn->identity_digest)))
+      rs->last_dir_503_at = now;
+    if ((ds = router_get_trusteddirserver_by_digest(conn->identity_digest)))
+      ds->fake_status.last_dir_503_at = now;
 
-      tor_free(body); tor_free(headers); tor_free(reason);
-      return -1;
-    }
-    /* XXXX022 Remove this once every server with bug 539 is obsolete. */
-    log_info(LD_DIR, "Server at '%s:%d' sent us a 503 response, but included "
-             "a body anyway.  We'll pretend it gave us a 200.",
-             conn->_base.address, conn->_base.port);
-    status_code = 200;
+    tor_free(body); tor_free(headers); tor_free(reason);
+    return -1;
   }
 
   plausible = body_is_plausible(body, body_len, conn->_base.purpose);