bw - fix redis error when using sessions and fix redis connection pool not used

src/bw/lua/bunkerweb/clusterstore.lua

@@ -70,7 +70,8 @@ function clusterstore:initialize(pool)
 		role = "master",
 		sentinels = {}
 	}
-	if pool == nil or pool then
+	self.pool = pool == nil or pool
+	if self.pool then
 		options.connection_options.pool = "bw-redis"
 		options.connection_options.pool_size = tonumber(self.variables["REDIS_KEEPALIVE_POOL"])
 	end

src/common/core/sessions/sessions.lua

@@ -73,7 +73,11 @@ function sessions:init()
 		if value == nil then
 			return self:ret(false, "can't get " .. k .. " variable : " .. err)
 		end
-		redis_vars[k] = value
+		if value == "" then
+			redis_vars[k] = nil
+		else
+			redis_vars[k] = value
+		end
 	end
 	-- Init configuration
 	local config = {