Aha, I managed to expand that backtrace a bit. The failure here isn't
quite what I was expecting:

starting phase `fix-symlinks'
Backtrace:
           8 (primitive-load
"/gnu/store/4sx0bpv580768j5i6g47gcfkb8kp2c12-ansible-2.8.1-guile-builder")
In ice-9/eval.scm:
   191:35  7 (_ _)
In ice-9/boot-9.scm:
    829:9  6 (catch _ _ #<procedure 7ffff5bac518 at
/gnu/store/qxai6lhbg2c4q37s5qf3cddwl0q61ng2-module-import/guix/build/gnu-build-system.scm:830:2
(key c)> _)
In srfi/srfi-1.scm:
   863:16  5 (every1 #<procedure 7ffff4d209e0 at
/gnu/store/qxai6lhbg2c4q37s5qf3cddwl0q61ng2-module-import/guix/build/gnu-build-system.scm:835:11
(expr)> ((fix-symlinks . #<procedure 7ffff4d0b3c0 at
ice-9/eval.scm:457:6 args>) (check . #<procedure check (#:key tests?
test-target use-setuptoo…>) …))
In
/gnu/store/qxai6lhbg2c4q37s5qf3cddwl0q61ng2-module-import/guix/build/gnu-build-system.scm:
   839:30  4 (_ _)
In ice-9/eval.scm:
    619:8  3 (_ #(#(#<directory (guile-user) 7ffff5c70140>) (("out" .
"/gnu/store/y36h6a36690lq6zvc3q3cf35ylmd95kr-ansible-2.8.1"))))
In ice-9/boot-9.scm:
   260:13  2 (for-each #<procedure 7fffefdb9620 at ice-9/eval.scm:333:13
(a)> ("config" "console" "doc" "galaxy" "inventory" "playbook" "pull"
"vault"))
In ice-9/eval.scm:
    619:8  1 (_ #(#(#<directory (guile-user) 7ffff5c70140>
"/gnu/store/y36h6a36690lq6zvc3q3cf35ylmd95kr-ansible-2.8.1") "config"))
In unknown file:
           0 (delete-file
"/gnu/store/y36h6a36690lq6zvc3q3cf35ylmd95kr-ansible-2.8.1/bin/.ansible-config-real")

ERROR: In procedure delete-file:
In procedure delete-file: No such file or directory