Allow `s3:upload_assets` to use site settings from DB take 2.

lib/tasks/s3.rake

@@ -37,8 +37,18 @@ def upload(path, remote_path, content_type, content_encoding = nil)
   end
 end
 
+def use_db_s3_config
+  ENV["USE_DB_S3_CONFIG"]
+end
+
 def helper
-  @helper ||= S3Helper.new(GlobalSetting.s3_bucket.downcase, '', S3Helper.s3_options(GlobalSetting))
+  @helper ||= begin
+    setting = use_db_s3_config ? SiteSetting : GlobalSetting
+
+    S3Helper.new(
+      setting.s3_bucket.downcase, '', S3Helper.s3_options(setting)
+    )
+  end
 end
 
 def assets
@@ -76,7 +86,7 @@ def asset_paths
 end
 
 def ensure_s3_configured!
-  unless GlobalSetting.use_s3? || ENV["USE_DB_S3_CONFIG"]
+  unless GlobalSetting.use_s3? || use_db_s3_config
     STDERR.puts "ERROR: Ensure S3 is configured in config/discourse.conf of environment vars"
     exit 1
   end