TagsPlugin tries to set property at wrong moment

The TagsPlugin tries to set a property "hippostd:tags" in the constructor if it's not there, i.e. if not provided by document prototype. As a published document node is not checked out in the initial view, (which it must be to be able to set a property), it leads to VersionException errors: cannot set property of a checked-in node.

So probably some condition has to be added