title: Ruby/RVM with @global gem - bundle run fails with `require': cannot load such file — bundler (LoadError)
body: <p>I study linux for 1 month. While I tried to make all steps from <a href="https://devcenter.heroku.com/articles/heroku-mysql" rel="noreferrer">Migrating from MySQL to Postgres on Heroku</a> I've got an error I could not handle.</p>
  <p>When I try to install  the <code>mysqltopostgres</code> gem from source:</p>
  <pre><code>$ git clone https://github.com/maxlapshin/mysql2postgres.git
  $ cd mysql2postgres
  $ bundle install
  $ gem build mysqltopostgres.gemspec
  $ sudo gem install mysqltopostgres-0.2.20.gem
  </code></pre>
  <p>I have an error on <code>$ bundle install</code> :</p>
  <pre><code>/home/franchb/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/
  kernel_require.rb:55:in `require': cannot load such file -- bundler (LoadError) 
  from /home/franchb/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/rubygems/core_ext/
  kernel_require.rb:55:in `require'
  from /usr/bin/bundle:7:in `&lt;main&gt;'
  </code></pre>
  <p>I've installed <code>sudo apt-get install bundler</code> but when i try enter <code>bundle -v</code> I get the same error!</p>
  <p>My <code>gem env</code> is:</p>
  <pre><code>RubyGems Environment:
    - RUBYGEMS VERSION: 2.5.1
    - RUBY VERSION: 2.3.0 (2015-12-25 patchlevel 0) [x86_64-linux]
    - INSTALLATION DIRECTORY: /home/franchb/.rvm/gems/ruby-2.3.0@global
    - USER INSTALLATION DIRECTORY: /home/franchb/.gem/ruby/2.3.0
    - RUBY EXECUTABLE: /home/franchb/.rvm/rubies/ruby-2.3.0/bin/ruby
    - EXECUTABLE DIRECTORY: /home/franchb/.rvm/gems/ruby-2.3.0@global/bin
    - SPEC CACHE DIRECTORY: /home/franchb/.gem/specs
    - SYSTEM CONFIGURATION DIRECTORY: /home/franchb/.rvm/rubies/ruby-2.3.0/etc
    - RUBYGEMS PLATFORMS:
      - ruby
      - x86_64-linux
    - GEM PATHS:
       - /home/franchb/.rvm/gems/ruby-2.3.0@global
    - GEM CONFIGURATION:
       - :update_sources =&gt; true
       - :verbose =&gt; true
       - :backtrace =&gt; false
       - :bulk_threshold =&gt; 1000
    - REMOTE SOURCES:
       - https://rubygems.org/
    - SHELL PATH:
       - /home/franchb/.rvm/gems/ruby-2.3.0@global/bin
       - /home/franchb/.rvm/rubies/ruby-2.3.0/bin
       - /home/franchb/.rvm/bin
       - /home/franchb/bin
       - /usr/local/sbin
       - /usr/local/bin
       - /usr/sbin
       - /usr/bin
       - /sbin
       - /bin
       - /usr/games
       - /usr/local/games
  </code></pre>
  <p>My <code>rvm gemset list</code> is</p>
  <pre><code>gemsets for ruby-2.3.0 (found in /home/franchb/.rvm/gems/ruby-2.3.0)
     (default)
  =&gt; global
     rails230
  </code></pre>
  <p>My gem list is</p>
  <pre><code>*** LOCAL GEMS ***
  
  bigdecimal (1.2.8)
  bundler-unload (1.0.2)
  did_you_mean (1.0.0)
  executable-hooks (1.3.2)
  gem-wrappers (1.2.7)
  io-console (0.4.5)
  json (1.8.3)
  minitest (5.8.3)
  net-telnet (0.1.1)
  power_assert (0.2.6)
  psych (2.0.17)
  rake (10.4.2)
  rdoc (4.2.1)
  rubygems-bundler (1.4.4)
  rvm (1.11.3.9)
  test-unit (3.1.5)
  </code></pre>
  <p>I use Linux Mint 17.3</p>
  <p>Please, help me to understand what goes wrong. I need to install <code>mysqltopostgres</code> to migrate MySQL to Posgres in Heroku.</p>
  <p>Thank you!</p>