在需要activerecord后需要失败Ruby

Question

我不能要求＆＃39; mongo＆＃39;和＆＃39; redis＆＃39;在我要求＆＃39; active_record＆＃39;之后。 是否有人遇到过这类问题以及如何解决？

# irb
irb(main):001:0> require 'mongo'
=> true
irb(main):002:0> require 'active_record'
=> true
irb(main):003:0> exit
# irb
irb(main):001:0> require 'active_record'
=> true
irb(main):002:0> require 'mongo'
oadError: cannot load such file -- mongo
    from /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:128:in `require'
    from /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:128:in `rescue in require'
    from /usr/local/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:39:in `require'
    from (irb):2
    from /usr/local/bin/irb:11:in `<main>'
irb(main):003:0>

要求＆＃39; mongo＆＃39;工作正常。首先要求＆＃39; active_record＆＃39;之后，在倒车时发生错误

更新

当我使用index.alauda.cn/library/ruby:2.2.3和index.alauda.cn/library/ruby:2.2.0正常工作而没有此问题时，问题就出现了。