我正在尝试安装bundle 1.5.2版，但在获取正确版本时遇到了一些麻烦。奇怪的是，当我使用gem安装捆绑程序时，尽管this回答说它们应该是相同的，但我得到了bundle和bundler的两个不同版本。以下是一些显示奇怪行为的命令：
$ which bundle
$ which bundler
$ gem install bundler -v 1.5.2
Fetching: bundler-1.5.2.gem (100%)
Successfully installed bundler-1.5.2
1 gem installed
Installing ri documentation for bundler-1.5.2...
Building YARD (yri) index for bundler-1.5.2...
Installing RDoc documentation for bundler-1.5.2...
$ bundle -v
Bundler version 1.5.2
$ bundler -v
Warning: No private key present, creating unsigned gem.
Warning: No private key present, creating unsigned gem.
Warning: No private key present, creating unsigned gem.
It's recommended to use Bundler through 'bundle' binary instead of 'bundler'
Bundler version 1.16.2
$ which bundler
/Users/me/.rvm/gems/ruby-2.2.0@my-gem-set/bin/bundler
$ which bundle
/Users/me/.rvm/gems/ruby-2.2.0@my-gem-set/bin/bundle
有什么想法为什么我会为bundle和bundler使用不同的版本？