PIWIK reports IOS 4.2

It is found that PIWIK reports analytic data for IOS 4.2.1.

It also reports data for versions above 4.2.1.(eg:8 and 9). When checked it is found that though we are using iOS 9.1 PIWIK displays it as iOS 4.2.1. What could be the reason for this? Is this a PIWIK bug?