gistfile1.txt

under RVM 1.8.7: 

MBP:oss ed$ ruby -rubygems test.rb 
Successfully installed thor-0.12.3
1 gem installed
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:31: warning: already initialized constant EXPR_BEG
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:32: warning: already initialized constant EXPR_MID
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:33: warning: already initialized constant EXPR_END
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:34: warning: already initialized constant EXPR_ARG
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:35: warning: already initialized constant EXPR_FNAME
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:36: warning: already initialized constant EXPR_DOT
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:37: warning: already initialized constant EXPR_CLASS
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:262: warning: already initialized constant TokenDefinitions
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:267: warning: already initialized constant TkReading2Token
/Users/ed/.rvm/ruby-1.8.7-p248/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:268: warning: already initialized constant TkSymbol2Token
ERROR:  While executing gem ... (NameError)
    uninitialized constant RubyToken::AlreadyDefinedToken

###############################

Under system ruby (1.8.7):

MBP:oss ed$ ruby -rubygems test.rb 
WARNING:  Installing to ~/.gem since /Library/Ruby/Gems/1.8 and
	  /usr/bin aren't both writable.
WARNING:  You don't have /Users/ed/.gem/ruby/1.8/bin in your PATH,
	  gem executables will not run.
Successfully installed thor-0.12.3
1 gem installed
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:31: warning: already initialized constant EXPR_BEG
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:32: warning: already initialized constant EXPR_MID
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:33: warning: already initialized constant EXPR_END
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:34: warning: already initialized constant EXPR_ARG
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:35: warning: already initialized constant EXPR_FNAME
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:36: warning: already initialized constant EXPR_DOT
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:37: warning: already initialized constant EXPR_CLASS
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:262: warning: already initialized constant TokenDefinitions
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:267: warning: already initialized constant TkReading2Token
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/rdoc/parsers/parse_rb.rb:268: warning: already initialized constant TkSymbol2Token
ERROR:  While executing gem ... (NameError)
    uninitialized constant RubyToken::AlreadyDefinedToken