bug#42009: package.cache not deterministic

[Ludovic Courtès]

Hi,

Most likely the problem with non-reproducible .go files is that the fix
for <https://bugs.gnu.org/20272> was incomplete.  In particular, I think
that gensyms are not reproducible when building things in parallel,
because the gensym depends on what’s loaded vs. interpreted.

Example of a simpler discrepancy:

--8<---------------cut here---------------start------------->8---
$ guix challenge guile-gcrypt
/gnu/store/i6zzgsjjlqyfn9zmanb55hqdackhc0mf-guile-gcrypt-0.3.0 contents differ:
  local hash: 0bkxim5532bd234iqxvxd31ybp6v7rmbrvyj3jrgpmgxbsw7hmxj
  
https://ci.guix.gnu.org/nar/lzip/i6zzgsjjlqyfn9zmanb55hqdackhc0mf-guile-gcrypt-0.3.0:
 00zsccxn1485bnvxvssgq50i2w69i38m9hnrk8z1sji9qcmmaxcs
  differing files:
    /lib/guile/3.0/site-ccache/gcrypt/pk-crypto.go
    /lib/guile/3.0/site-ccache/gcrypt/mac.go
--8<---------------cut here---------------end--------------->8---

HTH!

Ludo’.