Thanks to using own python with own libraries, there will be library version
conflicts, as lxml is built against own libz.

Thanks to using own python with own libraries, there will be library version
conflicts, as lxml is built against own libz.

It is required to override-update command as section is being update.

As slapos.cookbook provides different modules it is required to correctly
select when egg is wanted and when its module selected.

This is workaround for SlapOS limitation of development environment.