lib/fluent/plugin/grok.rb in fluent-plugin-grok-parser-2.4.0 vs lib/fluent/plugin/grok.rb in fluent-plugin-grok-parser-2.5.0

@@ -129,10 +129,10 @@
           replacement_pattern = "(?<#{m["subname"]}>#{curr_pattern})"
           type_map[m["subname"]] = m["type"] || "string"
         else
           replacement_pattern = "(?:#{curr_pattern})"
         end
-        pattern.sub!(m[0]) do |s|
+        pattern = pattern.sub(m[0]) do |s|
           replacement_pattern
         end
       end
 
       [pattern, type_map]