Some other changes.

.gitignore

 *.pyc
 /metrics
+Gemfile.lock

puma/Gemfile

+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gem 'puma', git: 'https://github.com/puma/puma.git', :branch => 'master'

puma/run.sh

+#! /bin/sh
+
+test -f Gemfile.lock && rm Gemfile.lock
+DEBUG_RESOLVER=1 bundle install

ruby/Gemfile.lock

-GIT
-  remote: https://github.com/lyda/mmap.git
-  revision: 5d7015bae9b841ae798982c175ffa9f018887405
-  branch: non-global-version
-  specs:
-    mmap (0.2.7b)
-
-GEM
-  remote: https://rubygems.org/
-  specs:
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  mmap!
-
-BUNDLED WITH
-   1.14.3

ruby/run.sh

 #! /bin/sh
 
 test -f Gemfile.lock && rm Gemfile.lock
-DEBUG_RESOLVER=1 bundle install
+DEBUG_RESOLVER=2 bundle install
 bundle exec ruby test.rb