rake 0.9.2.2 does not exist in rubygems.org
1.9.3 installs rake as a 'default gems' which version is 0.9.2.2, but the version does not exist in RubyGems's source repository.
I heard that it makes bundler confuse. For some environment (not 100%), bundler generates Gemfile.lock with 'rake 0.9.2.2' and it crashes because it's not in rubygems.org.
create the following 2-lines Gemfile
It creates '0.9.2.2' Gemfile.lock for some environment. (gem cache related? I'm not sure at present)
It might be just a bug of somewhere (ruby, rubygems, bundler, etc.), and should be fixed, but I think that this is an issue about "importing third party's gem as a standard library". It would be happened for json as well in the future.
I propose to remove 'rake' from 'default gems' for 1.9.3 GA (It just works as same as before like other standard libraries.) And the next version (1.9.4 or 2.0) should have a better way to integrate.