[Minor] Avoid pre-result overriding

src/plugins/lua/dmarc.lua

@@ -198,6 +198,8 @@ local function dmarc_callback(task)
   local function maybe_force_action(disposition)
     local force_action = dmarc_actions[disposition]
     if force_action then
+      -- Don't do anything if pre-result has been already set
+      if task:has_pre_result() then return end
       task:set_pre_result(force_action, 'Action set by DMARC')
     end
   end

src/plugins/lua/greylist.lua

@@ -249,6 +249,9 @@ local function greylist_set(task)
   local action = task:get_metric_action('default')
   local ip = task:get_ip()
 
+  -- Don't do anything if pre-result has been already set
+  if task:has_pre_result() then return end
+
   if settings.greylist_min_score then
     local score = task:get_metric_score('default')[1]
     if score < settings.greylist_min_score then

src/plugins/lua/ratelimit.lua

@@ -402,6 +402,9 @@ local function ratelimit_cb(task)
     end
   end
 
+  -- Don't do anything if pre-result has been already set
+  if task:has_pre_result() then return end
+
   if nprefixes > 0 then
     -- Save prefixes to the cache to allow update
     task:cache_set('ratelimit_prefixes', prefixes)
@@ -570,7 +573,7 @@ if opts then
     local s = {
       type = 'prefilter,nostat',
       name = 'RATELIMIT_CHECK',
-      priority = 4,
+      priority = 7,
       callback = ratelimit_cb,
       flags = 'empty',
     }