> > > Does it work to inherit the custom install phase from dragonfly-
> > > reverb?
> > > It seems like the install-file procedures would not apply here.
> 
> However, I tried building it from the patch and the install phase
> does
> fail there.

Did you build it after applying the previous 2 patches? 
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=40466 and
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=40467

This is supposed to be merged after those changes. The first patch
(40466) changes the install procedure in dragonfly-reverb, which is
inherited here.