问Bundler安装调试器1.6.8失败

EN

funk@funktop ~/rails_projects/hearingtracker $ gem install debugger -v '1.6.8'
Fetching: columnize-0.8.9.gem (100%)
Successfully installed columnize-0.8.9
Fetching: debugger-ruby_core_source-1.3.5.gem (100%)
Successfully installed debugger-ruby_core_source-1.3.5
Fetching: debugger-linecache-1.2.0.gem (100%)
Successfully installed debugger-linecache-1.2.0
Fetching: debugger-1.6.8.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing debugger:
    ERROR: Failed to build gem native extension.

    /home/funk/.rvm/rubies/ruby-2.1.2/bin/ruby extconf.rb
*** extconf.rb failed ***
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.

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/funk/.rvm/rubies/ruby-2.1.2/bin/ruby
/home/funk/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in `stat': No such file or directory @ rb_file_s_stat - ./212/ruby_debug.h (Errno::ENOENT)
    from /home/funk/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in `block in fu_each_src_dest'
    from /home/funk/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1587:in `fu_each_src_dest0'
    from /home/funk/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:1571:in `fu_each_src_dest'
    from /home/funk/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/fileutils.rb:399:in `cp'
    from extconf.rb:83:in `block in <main>'
    from extconf.rb:82:in `each'
    from extconf.rb:82:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /home/funk/.rvm/gems/ruby-2.1.2/gems/debugger-1.6.8 for inspection.
Results logged to /home/funk/.rvm/gems/ruby-2.1.2/extensions/x86_64-linux/2.1.0/debugger-1.6.8/gem_make.out