Rakefile in bundleup-0.8.1 vs Rakefile in bundleup-0.9.0

@@ -19,20 +19,22 @@
 
 task bump: %w[bump:bundler bump:ruby bump:year]
 
 namespace :bump do
   task :bundler do
-    version = Gemfile.bundler_version
+    version = Gem.latest_version_for("bundler").to_s
     replace_in_file ".travis.yml", /bundler -v (\S+)/ => version
+    replace_in_file "Gemfile.lock", /^BUNDLED WITH\n\s+([\d\.]+)$/ => version
   end
 
   task :ruby do
     lowest = RubyVersions.lowest_supported
     lowest_minor = RubyVersions.lowest_supported_minor
 
     replace_in_file "bundleup.gemspec", /ruby_version = ">= (.*)"/ => lowest
     replace_in_file ".rubocop.yml", /TargetRubyVersion: (.*)/ => lowest_minor
+    replace_in_file "README.md", /Ruby (\d+\.\d+)/ => lowest_minor
 
     travis = YAML.safe_load(open(".travis.yml"))
     travis["rvm"] = RubyVersions.latest_supported_patches + ["ruby-head"]
     IO.write(".travis.yml", YAML.dump(travis))
   end
@@ -56,24 +58,10 @@
     end
   end
   IO.write(path, contents) if contents != orig_contents
 end
 
-module Gemfile
-  class << self
-    def bundler_version
-      lock_file[/BUNDLED WITH\n   (\S+)$/, 1]
-    end
-
-    private
-
-    def lock_file
-      @_lock_file ||= IO.read("Gemfile.lock")
-    end
-  end
-end
-
 module RubyVersions
   class << self
     def lowest_supported
       "#{lowest_supported_minor}.0"
     end
@@ -93,10 +81,10 @@
 
     private
 
     def versions
       @_versions ||= begin
-        yaml = open(
+        yaml = URI.open(
           "https://raw.githubusercontent.com/ruby/www.ruby-lang.org/master/_data/downloads.yml"
         )
         YAML.safe_load(yaml, symbolize_names: true)
       end
     end