bug#53594: no matching pattern #<package polkit..

[Josselin Poiret via Bug reports for GNU Guix <bug-guix@gnu.org>]

Hello everyone,

Someone reported the exact same issue today on IRC [1], with polkit
being the culprit.  With a bigger backtrace, the match error happens at
line 901 in guix/gexp.scm, in the match inside the return part of
lower-inputs.  This suggests that lower-object doesn't manage to return
a derivation but only the polkit package.  I suspect that this has to do
with the complex polkit package interactions that we have, with polkit
being an identifier syntax for either polkit-mozjs or polkit-duktape,
with duktape package/inherit'ing polkit-mozjs with is itself replaced by
polkit-mozjs/fixed.

Maybe there's an interaction with the caching as well, while grafting
and looping?

I've tried to reproduce this locally by building a gexp that has either
polkit, polkit-duktape or polkit-mozjs as an input, enabling or
disabling fallback or grafting, to no avail.

Maybe someone else has another idea?

[1] https://logs.guix.gnu.org/guix/2022-04-22.log#154402

Best,
-- 
Josselin Poiret