What seems to have happened is that gem_runner is no longer required
automatically when you require rubygems. It appears to be an
intentional change in rubygems, as a part of "slimming" it down for
inclusion in 1.9
http://blog.segment7.net/articles/category/rubygems
The trivial fix is to add a line to require the rubygems/gem_runner.rb
in railties/lib/tasks/framework.rake
A quick check of the rubygems commit logs reveals that there could be
a fix down the line (r1515 will apparently "faults in the full
rubygems library if any Gem constant or method is called.") so it
might not be worthwhile actually patching this.
Anyway:
Index: railties/lib/tasks/framework.rake
===================================================================
--- railties/lib/tasks/framework.rake (revision 8220)
+++ railties/lib/tasks/framework.rake (working copy)
@@ -4,6 +4,7 @@
task :gems do
deps = %w(actionpack activerecord actionmailer activesupport
actionwebservice)
require 'rubygems'
+ require 'rubygems/gem_runner'
Gem.manage_gems
rails = (version = ENV['VERSION']) ?