Rename base image

Just a test.

Dockerfile

-FROM registry.git.autistici.org/ai3/docker/s6-base:master AS base
+FROM registry.git.autistici.org/ai3/docker/s6-base:master AS fbl-base
 RUN apt-get -q update && \
     env DEBIAN_FRONTEND=noninteractive apt-get -qy install --no-install-recommends \
         python3-flask python3-sqlalchemy python3-flask-sqlalchemy python3-cheroot \
@@ -6,12 +6,12 @@ RUN apt-get -q update && \
     apt-get clean && \
     rm -fr /var/lib/apt/lists/*
 
-FROM base AS build
+FROM fbl-base AS build
 ADD . /src
 WORKDIR /src
 RUN python3 setup.py bdist_wheel
 
-FROM base
+FROM fbl-base
 COPY --from=build /src/dist/*.whl /tmp/wheels/
 COPY conf/ /etc/
 COPY feedbackloop.sh /usr/local/bin/feedbackloop