bug#42127: collision in relocatable gcc-toolchain with gnupg

[Andrius Štikonas]

I was building a guix pack with

guix pack --symlink=/bin=bin --relocatable --relocatable --no-substitutes 
gcc-toolchain gnupg

and got the following error

Backtrace:
           3 (primitive-load "/gnu/store/n8zm1bjf4mrz4250c51ljasy8pc…")
In guix/build/profiles.scm:
    157:2  2 (build-profile "/gnu/store/9rqqgpv3nq5nqs9yik9zlzniz9q…" …)
In unknown file:
           1 (hash-for-each #<procedure 7fffefbb9f40 at guix/build/…> …)
In guix/build/union.scm:
   144:11  0 (_ _ _)

guix/build/union.scm:144:11: union-build: collision between file and 
directories ((files 
("/gnu/store/rgyjhfkb5sxcyy362i3bshh80v6giq2c-gcc-toolchain-10.1.0R/sbin")) 
(dirs ("/gnu/store/i1339a5cj1y53z3zgny2wls47kxzy48r-gnupg-2.2.20R/sbin")))

/gnu/store/rgyjhfkb5sxcyy362i3bshh80v6giq2c-gcc-toolchain-10.1.0R/sbin seems to 
be a statically linked executable
even though
3kvnslc16sy7kwi2c5r7r5k6bbv2p03f-gcc-toolchain-10.1.0/sbin is a symlink 
pointing to /gnu/store/fa6wj5bxkj5ll1d7292a70knmyl7a0cr-glibc-2.31/sbin

This makes gcc-toolchain and gnupg non co-installable.