[bundler/bundler] Remove old rubies stuff no longer needed

https://github.com/bundler/bundler/commit/36fb3287f4

lib/bundler/cli/exec.rb

@@ -13,7 +13,7 @@ module Bundler
       @cmd = args.shift
       @args = args
 
-      if Bundler.current_ruby.ruby_2? && !Bundler.current_ruby.jruby?
+      if !Bundler.current_ruby.jruby?
         @args << { :close_others => !options.keep_file_descriptors? }
       elsif options.keep_file_descriptors?
         Bundler.ui.warn "Ruby version #{RUBY_VERSION} defaults to keeping non-standard file descriptors on Kernel#exec."

lib/bundler/spec_set.rb

@@ -162,11 +162,7 @@ module Bundler
     end
 
     def extract_circular_gems(error)
-      if Bundler.current_ruby.mri? && Bundler.current_ruby.on_19?
-        error.message.scan(/(\w+) \([^)]/).flatten
-      else
-        error.message.scan(/@name="(.*?)"/).flatten
-      end
+      error.message.scan(/@name="(.*?)"/).flatten
     end
 
     def lookup

spec/bundler/bundler/dsl_spec.rb

@@ -275,7 +275,7 @@ RSpec.describe Bundler::Dsl do
     end
   end
 
-  describe "Runtime errors", :unless => Bundler.current_ruby.on_18? do
+  describe "Runtime errors" do
     it "will raise a Bundler::GemfileError" do
       gemfile "raise RuntimeError, 'foo'"
       expect { Bundler::Dsl.evaluate(bundled_app("Gemfile"), nil, true) }.