title: why selenium throw error with chrome driver version 2.25 while I installed 2.20
body: <p>recently I want to execute my capybara test case with chrome instead of firefox on jenkins. (with selenium 2.39.0)
  However, after download chrome version 48, and chrome webdriver 2.20. I met below selenium exception from Jenkins:</p>
  
  <pre><code>/var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/response.rb:51:in `assert_ok': unknown error: Chrome version must be &gt;= 53.0.2785.0 (Selenium::WebDriver::Error::UnknownError)
  (Driver info: chromedriver=2.25.426927 (d0803376130bda68eb594d02ebaca4609e3f899e),platform=Linux 3.5.0-23-generic x86)
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/response.rb:15:in `initialize'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/http/common.rb:59:in `new'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/http/common.rb:59:in `create_response'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/http/default.rb:66:in `request'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/http/common.rb:40:in `call'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/bridge.rb:634:in `raw_execute'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/bridge.rb:99:in `create_session'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/remote/bridge.rb:68:in `initialize'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/chrome/bridge.rb:29:in `initialize'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/common/driver.rb:37:in `new'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver/common/driver.rb:37:in `for'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/selenium-webdriver-2.39.0/lib/selenium/webdriver.rb:67:in `for'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/capybara-2.6.0/lib/capybara/selenium/driver.rb:13:in `browser'
  from /var/lib/jenkins/workspace/test/srm-smokestack/spec/spec_helper.rb:289:in `&lt;top (required)&gt;'
  from /var/lib/jenkins/workspace/test/srm-smokestack/spec/features/engage/common/engage_common_multiple_channels_spec.rb:1:in `require'
  from /var/lib/jenkins/workspace/test/srm-smokestack/spec/features/engage/common/engage_common_multiple_channels_spec.rb:1:in `&lt;top (required)&gt;'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/configuration.rb:896:in `load'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/configuration.rb:896:in `block in load_spec_files'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/configuration.rb:896:in `each'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/configuration.rb:896:in `load_spec_files'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/command_line.rb:22:in `run'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/runner.rb:80:in `run'
  from /var/lib/jenkins/workspace/test/srm-smokestack/vendor/bundle/ruby/1.9.1/gems/rspec-core-2.14.7/lib/rspec/core/runner.rb:17:in `block in autorun'
  </code></pre>
  
  <p>I am just don't know why I installed chromedriver 2.20, but the selenium just throw exception with:</p>
  
  <pre><code>Driver info: chromedriver=2.25.426927 
  </code></pre>
  
  <p>If I run chromedriver -v, I will get the 2.20 shows indeed:</p>
  
  <pre><code>ChromeDriver 2.20.353141 (da3cb4b52d3a04ce079546eac4dc96182f58602b)
  </code></pre>
  
  <p>run which chromedriver, will returned below location, which I already export /usr/local/bin to the $PATH:</p>
  
  <pre><code>/usr/local/bin/chromedriver
  </code></pre>