Fix rubocop on ruby-head

Author: byroot

Gemfile

@@ -10,6 +10,7 @@ gem "debug"
 gem "rake", "~> 13.0"
 
 gem "rubocop", "~> 1.21"
+gem "ostruct" # For rubocop
 gem "base64" # For rubocop
 
 gem "redis-client", ">= 0.22"

Gemfile.lock

@@ -12,6 +12,7 @@ GEM
     debug (0.2.1)
     json (2.7.2)
     json (2.7.2-java)
+    ostruct (0.6.1)
     parallel (1.24.0)
     parser (3.3.3.0)
       ast (~> 2.4.1)
@@ -53,6 +54,7 @@ DEPENDENCIES
   base64
   debug
   megatest!
+  ostruct
   rake (~> 13.0)
   redis-client (>= 0.22)
   rubocop (~> 1.21)