Hello, attached is a package definition that fails because substitute*
throws an error. The file I try to substitute* on has some names with
special signs like ë and é that might be related?
I also included a sed workaround which can be uncommented and works
perfectly fine, so the itself file is not too broken to be edited and
this is a bug with substitute*.

The file in question is: src/main.cc from
https://sourceforge.net/projects/eureka-editor/files/Eureka/1.21/eureka-121-source.tar.gz/download

I tested this on the latest guix master. git log says:

commit 7c0926ea7c6f0d0fa291251017704dfb6fb21924 (origin/master,
origin/HEAD, eureka)
Author: Ludovic Courtès <ludo@gnu.org>
Date:   Sat Jan 13 00:57:52 2018 +0100