ci: use old poetry installer

because this breaks installation of our docs theme
python-poetry/poetry#7358
pradyunsg/sphinx-theme-builder#39

dev/Containerfile-ci

@@ -8,6 +8,12 @@ RUN apt-get install -y --no-install-recommends curl rustc cargo gcc libssl-dev m
 RUN python3 -m pip install wheel pybindgen
 RUN curl -fL https://install.python-poetry.org | python3 - || cat /poetry-installer-error-*
 
+ENV PATH=/root/.local/bin:$PATH
+# furo (sphinx theme) cannot install without that,
+# cf https://github.com/python-poetry/poetry/pull/7358
+RUN poetry config installer.modern-installation false
+RUN poetry config experimental.new-installer true
+
 ENV GOBIN="/usr/local/bin"
 RUN go install github.com/go-python/gopy@latest && \
     go install golang.org/x/tools/cmd/goimports@latest
@@ -22,7 +28,6 @@ COPY tests/ /build/tests
 COPY dev/ /build/dev
 COPY docs/ /build/docs
 
-ENV PATH=/root/.local/bin:$PATH
 ARG TARGETARCH
 RUN poetry build
 RUN if [ "$TARGETARCH" = "amd64" ]; then \

docs/source/dev/general.rst

@@ -25,6 +25,19 @@ of XEPs, especially when it comes to components.
 You can launch it with the ``-p`` option to use a clean profile and not mess up
 your normal user settings and such.
 
+Poetry
+------
+
+To install outside of a container, use `poetry <https://python-poetry.org/>`_.
+
+Starting from poetry >= 1.4.0, these extra configuration steps are required, cf
+https://github.com/python-poetry/poetry/pull/7358
+
+.. code-block::
+
+   poetry config installer.modern-installation false
+   poetry config experimental.new-installer true
+
 Contributing
 ------------