Attribute release consent failing (sometimes)

[Manuel Haim]

FWIW, I've finally decided to put an error message on the login page if
the user agent matches any of

Chrome 53.0.2785.143 - released 31-Aug-2016
Chrome 54.0.2840.71 - released 12-Oct-2016
Safari 10.0 - released 20-Sep-2016
Safari 10.0.1 - released 24-Oct-2016
Firefox 49.0 - released 20-Sep-2016

login.vm, attribute-release.vm:
#set($userAgent = $request.getHeader("User-Agent"))
#if($userAgent.matches(".*(Chrome/53.0|Chrome/54.0|Version/10.0
Safari|Version/10.0.1 Safari|Firefox/49.0).*"))
  #springMessageText("my-browser-outdated", "Unsupported browser!")
#end

messages.properties:
my-browser-outdated=<strong>WARNING: Your browser is outdated and
unsupported by Web-Login!</strong><br>The following browser versions
were reported to cause errors during Web-Login, especially when trying
to access the service <em>XYZ</em>:<ul><li>Chrome
53.0.2785.143</li><li>Chrome 54.0.2840.71</li><li>Safari
10.0</li><li>Safari 10.0.1</li><li>Firefox 49.0</li></ul><strong>Please
update your browser software <em>before</em> trying to login!</strong>

Kind regards,
Manuel