Invalid gem format

I’m having some issues installing gems such as Thin. Please see debug
below:

XXXXX@laptop:~$ sudo gem install sup --debug -V
Exception NameError' at /usr/lib/ruby/1.8/rubygems/command_manager.rb:161 - uninitialized constant Gem::Commands::InstallCommand Exception Gem::LoadError’ at /usr/lib/ruby/1.8/rubygems.rb:827 - Could
not find RubyGem test-unit (>= 0)

Exception `Gem::LoadError’ at /usr/lib/ruby/1.8/rubygems.rb:827 - Could
not find RubyGem sources (> 0.0.1)

GET 200 OK: RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK: RubyGems.org | your community gem host
Exception EOFError' at /usr/lib/ruby/1.8/net/protocol.rb:135 - end of file reached Exception EOFError’ at /usr/lib/ruby/1.8/net/protocol.rb:120 - end of
file reached
connection reset after 10 requests, retrying
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
GET 200 OK:
RubyGems.org | your community gem host
Installing gem ferret-0.11.6
Exception Gem::Package::FormatError' at /usr/lib/ruby/1.8/rubygems/package/tar_input.rb:110 - No metadata found! Exception Gem::InstallError’ at
/usr/lib/ruby/1.8/rubygems/installer.rb:121 - invalid gem format for
/var/lib/gems/1.8/cache/ferret-0.11.6.gem
ERROR: Error installing sup:
invalid gem format for /var/lib/gems/1.8/cache/ferret-0.11.6.gem