[bug#49181] [PATCH core-updates v2] guix: Make modify-phases error when adding before/after a missing phase

[Carlo Zancanaro]

Ping!

Given the upcoming planned world rebuild, it would be nice to get 
this into core-updates.

On Sat, May 20 2023, Carlo Zancanaro wrote:
> * guix/build/utils.scm (alist-cons-before, alist-cons-after): 
> Cause a match failure if the
> reference is not found, rather than appending to the alist.
> * tests/build-utils.scm: Update tests to match.
> ---
>  guix/build/utils.scm  | 15 +++++++++------
>  tests/build-utils.scm | 12 ++++++------
>  2 files changed, 15 insertions(+), 12 deletions(-)
> ...