bug#27476: guix pull fails on powerful server

["Clément Lassieur" <clement@lassieur.org>]

I got it too for the first time yesterday on my 128G RAM and 32 CPU
cores server:

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substitute: updating list of substitutes from [...]
Updating from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
Building from Git commit 3140844e33254316348135b03762eaeb04764544...
substitute: updating list of substitutes from [...]
The following derivation will be built:
   /gnu/store/7143x1dd2r5kch8dldyylz1ljhp3nird-guix-latest.drv
copying and compiling to '/gnu/store/8a42yc4yxslrr1hf7wk5x5mddbs76yqm-guix-latest' with Guile 2.2.2...
loading...       25.3% of 632 filesrandom seed for tests: 1506279202
loading...       99.8% of 632 files
compiling...     94.8% of 632 filesice-9/threads.scm:289:22: In procedure loop:
ice-9/threads.scm:289:22: Syntax error:
guix/gexp.scm:530:8: return: return used outside of 'with-monad' in form (return output)

Some deprecated features have been used.  Set the environment
variable GUILE_WARN_DEPRECATED to "detailed" and rerun the
program to get more information.  Set it to "no" to suppress
this message.
builder for `/gnu/store/7143x1dd2r5kch8dldyylz1ljhp3nird-guix-latest.drv' failed with exit code 1
guix pull: error: build failed: build of `/gnu/store/7143x1dd2r5kch8dldyylz1ljhp3nird-guix-latest.drv' failed
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And then, today, again:

--8<---------------cut here---------------start------------->8---
substitute: updating list of substitutes from [...]
Updating from Git repository at 'https://git.savannah.gnu.org/git/guix.git'...
Building from Git commit 66660960ba75233ae5b6c539f43d97d06d64e9ad...
substitute: updating list of substitutes from [...]
The following derivation will be built:
   /gnu/store/dmv64icdan1fqrl00czgwx1an923fzda-guix-latest.drv
copying and compiling to '/gnu/store/slqcrr5gwhi1zqv21wjp0l973zs3dywc-guix-latest' with Guile 2.2.2...
loading...       25.3% of 632 filesrandom seed for tests: 1506327995
loading...       99.8% of 632 files
compiling...     94.8% of 632 filesice-9/threads.scm:289:22: In procedure loop:
ice-9/threads.scm:289:22: Syntax error:
guix/gexp.scm:539:10: return: return used outside of 'with-monad' in form (return (derivation->output-path drv))

Some deprecated features have been used.  Set the environment
variable GUILE_WARN_DEPRECATED to "detailed" and rerun the
program to get more information.  Set it to "no" to suppress
this message.
builder for `/gnu/store/dmv64icdan1fqrl00czgwx1an923fzda-guix-latest.drv' failed with exit code 1
guix pull: error: build failed: build of `/gnu/store/dmv64icdan1fqrl00czgwx1an923fzda-guix-latest.drv' failed
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