Style sheet version management is broken

The style sheet version in bind9.xsl also needs to be updated when the contents change and the correct version needs to be requested when the .xml is returned. bind9.xsl in bind-9.18 is different to bind-9.20 so there should be different version numbers. The version identifier (as shown below) has not changed in several major versions but it should have.

<xsl:output method="html" indent="yes" version="4.0"/>

We need to fix at least 9.18 and 9.20 so that they are different to 9.16. Also the -sub versions also need to differ from the base versions.