It's usually some method called on a very large negative Fixnum. Note
below how different install runs produce different errors. (Who said
that computers were deterministic?)

[sliver:~/Desktop] gkistner$ sudo gem install facets
Successfully installed facets-1.7.46
Installing ri documentation for facets-1.7.46...
ERROR:  While executing gem ... (NoMethodError)
    undefined method `empty?' for -517611318:Fixnum

[sliver:~/Desktop] gkistner$ sudo gem uninstall facets
Successfully uninstalled facets version 1.7.46

[sliver:~/Desktop] gkistner$ sudo gem install facets --backtrace
ERROR:  While executing gem ... (NoMethodError)
    undefined method `shift' for -517611318:Fixnum
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:87:in
`new_from_stream'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:441:in
`each_entry'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:439:in `loop'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:439:in
`each_entry'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:424:in `each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:591:in `each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:411:in `new'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:590:in `each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:445:in
`each_entry'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:439:in `loop'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:439:in
`each_entry'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:424:in `each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:586:in `each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/format.rb:62:in `from_io'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:579:in
`open_from_io'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/package.rb:801:in
`open_from_io'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/format.rb:59:in `from_io'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/format.rb:47:in
`from_file_by_path'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/installer.rb:62:in `install'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/remote_installer.rb:444:in
`install'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:258:in
`execute'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:220:in
`each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:220:in
`execute'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/command.rb:69:in `invoke'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:117:in
`process_args'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:88:in `run'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_runner.rb:29:in `run'
/usr/local/bin/gem:23

[sliver:~/Desktop] gkistner$ sudo gem uninstall facets
ERROR:  While executing gem ... (RuntimeError)
    Unknown RubyGem: facets (> 0)

[sliver:~/Desktop] gkistner$ sudo gem install facets --backtrace
Successfully installed facets-1.7.46
Installing ri documentation for facets-1.7.46...


RDoc failure in lib/facets/more/cookie.rb at or around line 336 column
-517618807

Before reporting this, could you check that the file
you're documenting compiles cleanly--RDoc is not a
full Ruby parser, and gets confused easily if fed
invalid programs.

The internal error was:

While generating documentation for facets-1.7.46
... MESSAGE:   unget past beginning of file
... RDOC args: --ri --op
/usr/local/lib/ruby/gems/1.8/doc/facets-1.7.46/ri --quiet lib
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:395:in `ungetc'
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:508:in `ungetc'
/usr/local/lib/ruby/1.8/irb/slex.rb:234:in `match_io'
/usr/local/lib/ruby/1.8/irb/slex.rb:222:in `match_io'
(continuing with the rest of the installation)
Installing RDoc documentation for facets-1.7.46...
ERROR:  While executing gem ... (NoMethodError)
    undefined method `postproc' for -517611318:Fixnum
/usr/local/lib/ruby/1.8/irb/slex.rb:135:in `create_subnode'
/usr/local/lib/ruby/1.8/irb/slex.rb:147:in `create_subnode'
/usr/local/lib/ruby/1.8/irb/slex.rb:67:in `create'
/usr/local/lib/ruby/1.8/irb/slex.rb:39:in `def_rule'
/usr/local/lib/ruby/1.8/irb/slex.rb:47:in `def_rules'
/usr/local/lib/ruby/1.8/irb/slex.rb:46:in `each'
/usr/local/lib/ruby/1.8/irb/slex.rb:46:in `def_rules'
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:714:in `lex_init'
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:448:in `initialize'
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:1393:in `new'
/usr/local/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:1393:in `initialize'
/usr/local/lib/ruby/1.8/rdoc/parsers/parserfactory.rb:96:in `new'
/usr/local/lib/ruby/1.8/rdoc/parsers/parserfactory.rb:96:in
`parser_for'
/usr/local/lib/ruby/1.8/rdoc/rdoc.rb:209:in `parse_files'
/usr/local/lib/ruby/1.8/rdoc/rdoc.rb:203:in `each'
/usr/local/lib/ruby/1.8/rdoc/rdoc.rb:203:in `parse_files'
/usr/local/lib/ruby/1.8/rdoc/rdoc.rb:246:in `document'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/doc_manager.rb:101:in
`run_rdoc'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/doc_manager.rb:80:in
`install_rdoc'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/doc_manager.rb:58:in
`generate_rdoc'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:289:in
`execute'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:288:in
`each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:288:in
`execute'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:220:in
`each'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_commands.rb:220:in
`execute'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/command.rb:69:in `invoke'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:117:in
`process_args'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/cmd_manager.rb:88:in `run'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/gem_runner.rb:29:in `run'
/usr/local/bin/gem:23