First result is that the following patch will fix the build problem for the Dockerfile,
but we have not found out what caused the issue in the first place.
And we also do not know, if this is the correct fix.
Tests still fail afterwards.

(Analysis done by Christian Funke.)

diff -r c4db6e2ccc5e scripts/Docker/Dockerfile
--- a/scripts/Docker/Dockerfile Wed Sep 02 12:46:01 2026 -0400
+++ b/scripts/Docker/Dockerfile Fri Sep 04 16:49:02 2026 +0200
@@ -128,6 +128,7 @@
 #   modules not installed in the base library.
 # ignore warnings from pip to use virtualenv
 COPY scripts/Docker/requirements.txt .
+RUN pip install setuptools && pip install gpg --no-build-isolation
 RUN pip install --no-cache-dir -r requirements.txt
 
 # copy the elements of the release directory to the docker image