Thanks.

Also xfce4-pulseaudio-plugin (this breaks system configurations with
xfce-desktop-service):

  starting phase `augment-cflags'
  Backtrace:
             7 (primitive-load "/gnu/store/b01jl2cm2v4pbang81grgmhp7pi?")
  In ice-9/eval.scm:
     191:35  6 (_ #f)
  In ice-9/boot-9.scm:
      829:9  5 (catch srfi-34 #<procedure 7ffff60a4c20 at /gnu/store/?> ?)
  In srfi/srfi-1.scm:
     863:16  4 (every1 #<procedure 7ffff60a4be0 at /gnu/store/w3jlc8p?> ?)
  In /gnu/store/w3jlc8pk8416m7h677r5vq92b66h8cqd-module-import/guix/build/gnu-build-system.scm:
     839:30  3 (_ _)
  In ice-9/eval.scm:
      619:8  2 (_ #(#(#<directory (guile-user) 7ffff6c74140>) (# # ?)))
      159:9  1 (_ #(#(#<directory (guile-user) 7ffff6c74140>) (# # ?)))
  In unknown file:
             0 (string-append "/gnu/store/wz8zw92bs7a2r01n4msicwwk4sc?" ?)

  ERROR: In procedure string-append:
  In procedure string-append: Wrong type (expecting string): #f

Probably caused by use of C_INCLUDE_PATH instead of CPATH.

Would it be feasible to wait for CI to build everything in core-updates
and investigate all failures before merging?

-- 
Mikhail