title: Pry-doc installation on windows 8.1
body: <p>I have already installed pry on my windows 8.1 desktop. But to get access to Ruby Core documentation &amp; to use all features of pry, I am trying to install pry-doc, I am getting following error:</p>
  
  <pre><code>gem install pry-doc
  </code></pre>
  
  <blockquote>
    <p>ERROR:  Error installing pry-doc: invalid gem: package is corrupt,
    exception while verifying: undefined method 'size' for nil:NilClass
    (NoMethodError) in<br>
    h:/RailsInstaller/Ruby2.1.0/lib/ruby/gems/2.1.0/cache/pry-doc-0.8.0.gem</p>
  </blockquote>
  
  <p>I have following gems installed:</p>
  
  <pre><code>`gem list`
  
  *** LOCAL GEMS ***
  
  `abstract (1.0.0)
  actionmailer (4.1.8, 4.0.0.rc2, 3.0.9)
  actionpack (4.1.8, 4.0.0.rc2, 3.0.9)
  actionview (4.1.8)
  activemodel (4.1.8, 4.0.0.rc2, 3.0.9)
  activerecord (4.1.8, 4.0.0.rc2, 3.0.9)
  activerecord-deprecated_finders (1.0.4, 1.0.3)
  activerecord-sqlserver-adapter (4.1.0)
  activeresource (3.0.9)
  activesupport (4.1.8, 4.0.0.rc2, 3.0.9)
  arel (5.0.1.20140414130214, 4.0.2, 4.0.0, 2.0.10)
  atk (3.0.7 x86-mingw32)
  atomic (1.1.9)
  bcrypt (3.1.10 x86-mingw32)
  bcrypt-ruby (3.1.5 x86-mingw32, 3.0.1 x86-mingw32)
  bigdecimal (1.2.4)
  builder (3.2.2, 3.1.4, 2.1.2)
  bundler (1.7.7)
  cairo (1.14.3 x86-mingw32)
  coderay (1.1.0)
  coffee-rails (4.1.0, 4.0.1, 4.0.0)
  coffee-script (2.4.1, 2.3.0, 2.2.0)
  coffee-script-source (1.10.0, 1.9.1.1, 1.8.0, 1.6.2)
  devise (3.0.4, 3.0.0.rc)
  domain_name (0.5.25)
  erubis (2.7.0, 2.6.6)
  execjs (2.6.0, 2.2.2, 1.4.0)
  gdk_pixbuf2 (3.0.7 x86-mingw32)
  glib2 (3.0.7 x86-mingw32)
  green_shoes (1.1.374)
  gtk2 (3.0.7 x86-mingw32)
  hike (1.2.3)
  http-cookie (1.0.2)
  i18n (0.7.0, 0.7.0.beta1, 0.6.4, 0.5.0)
  io-console (0.4.2)
  jbuilder (2.3.2)
  jquery-rails (3.1.4, 3.1.2, 3.0.1)
  json (1.8.3, 1.8.1, 1.8.0, 1.6.1)
  kaminari (0.16.3, 0.14.1)
  mail (2.6.3, 2.5.4, 2.2.19)
  mechanize (2.7.3)
  method_source (0.8.2)
  mime-types (2.99, 2.6.2, 2.4.3, 1.25.1, 1.23, 1.17.1)
  mini_portile2 (2.0.0)
  minitest (5.8.3, 5.8.2, 5.4.3, 4.7.5, 4.7.4)
  multi_json (1.11.2, 1.10.1, 1.7.6)
  net-http-digest_auth (1.4)
  net-http-persistent (2.9.4)
  nokogiri (1.6.8.rc1 x86-mingw32)
  ntlm-http (0.1.1)
  orm_adapter (0.5.0, 0.4.0)
  pango (3.0.7 x86-mingw32)
  pg (0.17.1 x86-mingw32)
  pkg-config (1.1.6)
  polyglot (0.3.5, 0.3.3, 0.3.2)
  pry (0.10.3)
  psych (2.0.5)
  rack (1.5.5, 1.5.2, 1.2.4)
  rack-mount (0.6.14)
  rack-test (0.6.3, 0.6.2, 0.5.7)
  rails (4.1.8, 4.0.0.rc2, 3.0.9)
  railties (4.1.8, 4.0.0.rc2, 3.0.9)
  rake (10.4.2, 10.1.0, 10.0.4, 0.9.2.2)
  rb-readline (0.5.1)
  rdoc (4.2.0, 4.1.0, 3.12.2, 3.11)
  RedCloth (4.2.9 x86-mingw32)
  rubygems-update (2.2.3)
  rubyzip (1.1.6)
  sass (3.4.19, 3.2.19, 3.2.9)
  sass-rails (4.0.5, 4.0.0, 4.0.0.rc2)
  sdoc (0.4.1, 0.3.20)
  simple_form (3.0.0.rc)
  slop (3.6.0)
  sprockets (3.0.0.beta.4, 2.12.4, 2.12.3, 2.10.0)
  sprockets-rails (2.3.3, 2.2.1, 2.0.1, 2.0.0)
  sqlite3 (1.3.11 x86-mingw32, 1.3.10 x86-mingw32, 1.3.7 x86-mingw32, 1.3.4 x86-mingw32)
  sqlite3-ruby (1.3.3)
  test-unit (2.1.5.0)
  thor (0.19.1, 0.18.1, 0.14.6)
  thread_safe (0.3.5, 0.3.4, 0.1.0)
  tilt (1.4.1)
  treetop (1.4.15, 1.4.14, 1.4.10)
  turbolinks (2.5.3, 1.2.0)
  tzinfo (1.2.2, 0.3.46, 0.3.37, 0.3.30)
  tzinfo-data (1.2015.7)
  uglifier (2.7.2, 2.1.1)
  unf (0.2.0.beta2)
  warden (1.2.3, 1.2.1)
  webrobots (0.1.1)
  yard (0.8.7.6)
  zurb-foundation (4.2.3, 4.2.2)`
  </code></pre>