rake install fails but gem install works fine, any idea why? - ruby-on-rails-3

Question

The problem:
I have this gem that I am working on. While trying to install it locally to do some tests, rake install fails after building the gem. Rake suggested that I run gem install for the built gem to debug. Surprisingly, gem install pkg/my_gem-x.y.z.gem works like a charm!
Any idea why?
Some details:
rake version: 10.0.3
Gem created using bundler version: 1.2.1
Contents of gemspec:
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'my_gem/version'
Gem::Specification.new do |gem|
gem.name = "mygem"
gem.version = MyGem::VERSION
gem.authors = ["Omar Abdel-Wahab"]
gem.email = ["me#example.com"]
gem.description = %q{bla bla bla}
gem.summary = %q{bla bla bla}
gem.homepage = "http://github.com/foobar/"
gem.files = `git ls-files`.split($/)
gem.executables = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
gem.test_files = gem.files.grep(%r{^(test|spec|features)/})
gem.require_paths = ["lib"]
gem.add_dependency "rails", ">= 3.1"
gem.add_dependency "jquery-rails"
gem.add_dependency "twitter-bootstrap-rails", ">= 2.1.0"
gem.add_development_dependency "bundler", ">= 1.0.0"
gem.add_development_dependency "rspec", "~> 2.3"
gem.add_development_dependency "sqlite3-ruby"
end
Output from rake install:
~/Projects/Github/my_gem% rake -vt install
** Invoke install (first_time)
** Execute install
my_gem 0.0.1 built to pkg/my_gem-0.0.1.gem
rake aborted!
Couldn't install gem, run `gem install /Users/owahab/Projects/Github/my_gem/pkg/my_gem-0.0.1.gem' for more detailed output
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/bundler-1.2.1/lib/bundler/gem_helper.rb:68:in `install_gem'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/bundler-1.2.1/lib/bundler/gem_helper.rb:43:in `block in install'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:228:in `call'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:228:in `block in execute'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:223:in `each'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:223:in `execute'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:166:in `block in invoke_with_call_chain'
/Users/owahab/.rvm/rubies/ruby-1.9.3-p286/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:159:in `invoke_with_call_chain'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/task.rb:152:in `invoke'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:143:in `invoke_task'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:101:in `each'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:101:in `block in top_level'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:110:in `run_with_threads'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:95:in `top_level'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:73:in `block in run'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:160:in `standard_exception_handling'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/lib/rake/application.rb:70:in `run'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/rake-10.0.3/bin/rake:33:in `<top (required)>'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/bin/rake:19:in `load'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/bin/rake:19:in `<main>'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/bin/ruby_noexec_wrapper:14:in `eval'
/Users/owahab/.rvm/gems/ruby-1.9.3-p286/bin/ruby_noexec_wrapper:14:in `<main>'
Tasks: TOP => install
Output from rake build then gem install:
~/Projects/Github/rails_autocomplete% rake build && gem install pkg/my_gem-0.0.1.gem
my_gem 0.0.1 built to pkg/my_gem-0.0.1.gem
Successfully installed my_gem-0.0.1
1 gem installed
Installing ri documentation for my_gem-0.0.1...
Building YARD (yri) index for my_gem-0.0.1...
Installing RDoc documentation for my_gem-0.0.1...

Answer 1

Based on the comment thread on the question, it was a permission problem. Debugging Bundler's gem_helper.rb file revealed this:
ERROR: While executing gem ... (Errno::EACCES) Permission denied - /Users/owahab/.rvm/gems/ruby-1.9.3-p286/gems/i18n-0.6.1/ci/Gemfile.no-rails
Some gems had been installed as root. Removing them solved the problem.