title: debugger won't install Rails 4.1.5
body: <p>So I was trying to do a <code>bundle update</code> and I got:</p>
  
  <blockquote>
    <p>Gem::Ext::BuildError: ERROR: Failed to build gem native extension.</p>
  
  <pre><code>/home/adam/.rvm/rubies/ruby-2.1.2/bin/ruby extconf.rb 
  </code></pre>
    
    <p><strong>* extconf.rb failed *</strong> Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.  Check
    the mkmf.log file for more details.  You may need configuration
    options.</p>
    
    <p>Provided configuration options:   --with-opt-dir  --without-opt-dir
      --with-opt-include  --without-opt-include=${opt-dir}/include
      --with-opt-lib  --without-opt-lib=${opt-dir}/lib    --with-make-prog
      --without-make-prog     --srcdir=.  --curdir
      --ruby=/home/adam/.rvm/rubies/ruby-2.1.2/bin/ruby
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in
    <code>stat': No such file or directory @ rb_file_s_stat -
    ./212/ruby_debug.h (Errno::ENOENT)    from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in
    </code>block in fu_each_src_dest'   from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1587:in
    <code>fu_each_src_dest0'   from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1571:in
    </code>fu_each_src_dest'    from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:399:in
    <code>cp'  from extconf.rb:83:in</code>block in '     from extconf.rb:82:in
    <code>each'    from extconf.rb:82:in</code>'</p>
    
    <p>extconf failed, exit code 1</p>
    
    <p>Gem files will remain installed in
    /home/adam/.rvm/gems/ruby-2.1.2/gems/debugger-1.6.8 for inspection.
    Results logged to
    /home/adam/.rvm/gems/ruby-2.1.2/extensions/x86_64-linux/2.1.0/debugger-1.6.8/gem_make.out
    An error occurred while installing debugger (1.6.8), and Bundler
    cannot continue. Make sure that <code>gem install debugger -v '1.6.8'</code>
    succeeds before bundling.</p>
  </blockquote>
  
  <p>So I tried to do the following: <code>gem install debugger -v '1.6.8'</code> and got</p>
  
  <blockquote>
    <p>Building native extensions.  This could take a while... ERROR:  Error
    installing debugger:  ERROR: Failed to build gem native extension.</p>
  
  <pre><code>/home/adam/.rvm/rubies/ruby-2.1.2/bin/ruby extconf.rb
  </code></pre>
    
    <p><strong>* extconf.rb failed *</strong> Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.  Check
    the mkmf.log file for more details.  You may need configuration
    options.</p>
    
    <p>Provided configuration options:   --with-opt-dir  --without-opt-dir
      --with-opt-include  --without-opt-include=${opt-dir}/include
      --with-opt-lib  --without-opt-lib=${opt-dir}/lib    --with-make-prog
      --without-make-prog     --srcdir=.  --curdir
      --ruby=/home/adam/.rvm/rubies/ruby-2.1.2/bin/ruby
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in
    <code>stat': No such file or directory @ rb_file_s_stat -
    ./212/ruby_debug.h (Errno::ENOENT)    from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in
    </code>block in fu_each_src_dest'   from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1587:in
    <code>fu_each_src_dest0'   from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1571:in
    </code>fu_each_src_dest'    from
    /home/adam/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:399:in
    <code>cp'  from extconf.rb:83:in</code>block in '     from extconf.rb:82:in
    <code>each'    from extconf.rb:82:in</code>'</p>
    
    <p>extconf failed, exit code 1</p>
    
    <p>Gem files will remain installed in
    /home/adam/.rvm/gems/ruby-2.1.2/gems/debugger-1.6.8 for inspection.
    Results logged to
    /home/adam/.rvm/gems/ruby-2.1.2/extensions/x86_64-linux/2.1.0/debugger-1.6.8/gem_make.out</p>
  </blockquote>
  
  <p>I have 4 other rails apps all running 4.1.5 and they all have no issue with <code>bundle update</code> so what's going on?</p>