The setup scripts for python2-tagpy tries to make changes to the system at build-time (as opposed to installation-time). It also exists on the latest boost TODO and no other packages use it, except for it being an optional dependency for sonata.
Sonata is currently in [extra], maintained by Ángel Velásquez.
My assumption is that nobody is interested in adopting python2-tagpy and keeping it in [extra] or [community], so I'm going to move it to AUR unless there are any protests (which are followed up by adoptions).
I'll move the package after an arbitrary amount of time has passed (probably when it is among the last packages on the TODO list, and we want to get the upgrade to the latest version of boost going).