当我在rails项目目录中运行cap production deploy时，出现如下错误：
INFO[6be9dff4] Running RBENV_ROOT=/usr/local/rbenv RBENV_VERSION=2.1.1 /usr/local/rbenv/bin/rbenv exec bundle install --binstubs /var/www/example.com/shared/bin --path /var/www/example.com/shared/bundle --without development test --deployment --quiet on example.com
DEBUG[6be9dff4] Command: cd /var/www/example.com/releases/20140624143014 && ( RBENV_ROOT=/usr/local/rbenv RBENV_VERSION=2.1.1 RBENV_ROOT=/usr/local/rbenv RBENV_VERSION=2.1.1 /usr/local/rbenv/bin/rbenv exec bundle install --binstubs /var/www/example.com/shared/bin --path /var/www/example.com/shared/bundle --without development test --deployment --quiet )
DEBUG[6be9dff4] Errno::EACCES: Permission denied @ rb_sysopen - /var/www/example.com/shared/bundle/ruby/2.1.0/cache/rake-10.3.2.gem
DEBUG[6be9dff4] An error occurred while installing rake (10.3.2), and Bundler cannot continue.
DEBUG[6be9dff4] Make sure that `gem install rake -v '10.3.2'` succeeds before bundling.
所以我登录服务器并将用户更改为部署用户，然后运行如下命令：
$ su - deployer
Password:
deployer@server ~$ cd /var/www/example.com/releases/20140624143014 && ( RBENV_ROOT=/usr/local/rbenv RBENV_VERSION=2.1.1 RBENV_ROOT=/usr/local/rbenv RBENV_VERSION=2.1.1 /usr/local/rbenv/bin/rbenv exec bundle install --binstubs /var/www/example.com/shared/bin --path /var/www/example.com/shared/bundle --without development test --deployment --quiet )
Errno::EACCES: Permission denied @ rb_sysopen - /var/www/example.com/shared/bundle/ruby/2.1.0/cache/rake-10.3.2.gem
An error occurred while installing rake (10.3.2), and Bundler cannot continue.
Make sure that `gem install rake -v '10.3.2'` succeeds before bundling.
rbenv和ruby的安装方式如下：
$ rbenv versions
system
2.0.0-p451
* 2.1.1 (set by /usr/local/rbenv/version)
我使用LinuxMint16从CentOS 6.5部署到Capistrano 3并且在使用2.0.0-p451之前部署成功。
我应该如何检查以及找出导致错误的原因？