bug#39795: gtkspell3 substitution failure--also, format of error message

[Danny Milosavljevic]

Hi,

I get the following on guix package -u . with guix describe being

Generation 56   Feb 24 2020 16:19:39    (current)
  guix eab07e7
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: eab07e78b691ae7866267fc04d31c7c3ad6b0eeb

guix substitute: error: host name lookup error: Name or service not known
substitution of /gnu/store/21kizyzrfh0ysh1ihhzngcy9ysvlq4dy-gtkspell3-3.0.9 
failed
killing process 19078
killing process 19078: No such process
guix package: error: some substitutes for the outputs of derivation 
`/gnu/store/d18cxxd362rird73cylak2l7m3gzrz0i-gtkspell3-3.0.9.drv' failed 
(usually happens due to networking issues); try `--fallback' to build 
derivation from source 

Maybe we should improve the error message to also print the name of the host
that Guix was trying to resolve.

./guix/scripts/substitute.scm:          (leave (G_ "host name lookup error: 
~a~%")

pgpozQnLrTQOA.pgp
Description: OpenPGP digital signature