ThOr functors without parameters lose their docstring

I generated a summary of functors and their docstrings using a short script. The result is here: https://roneil.web.cern.ch/MooreNightly28May21_functor_docstrings.txt

I notice that functors such as X, Y, Z, ETA, which have no parameters, all have their __doc__ set to A functor that has had all its parameters fully specified. rather than their brief_docs value passed to Functors.grammar.Functor.

Additionally this can be seen when running

lb-run --platform x86_64-centos7-gcc9-opt --nightly lhcb-head/Today Moore/HEAD python

>>> import Functors as F
>>> help(F.ETA)

and ETA has a brief_docs set to Pseudorapidity. since

ETA = Functor('ETA', "Track::PseudoRapidity", "TrackLike.h", "Pseudorapidity.")