bug#47543: “Repeated allocation of very large block” during ‘guix pull’

[Ludovic Courtès]

While running ‘guix pull’, sometime between the actual ‘git pull’ (via
Guile-Git) and channel authentication, I saw the dreaded libgc warning:

  Repeated allocation of very large block

I forgot to capture the command output though, and it does not seem to
be reproducible.  (This is with a recent Guix,
ca. 9098745b181b3022587a35afd255f7ff1d41ac86.)

Running the command below from a Guix checkout, which authenticates 15+K
commits, isn’t enough to trigger it:

  guix git authenticate --cache-key=whatever \
    "9edb3f66fd807b096b48283debdcddccfea34bad" \
    "BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA"

So it might rather be ‘update-cached-checkout’ that triggers it.

If you experience it, please share the command line and command output!

Ludo’.