GH echo seems to let -e argument through. Trying to force core-utils' echo.
--- a/Dockerfile Fri May 20 13:38:48 2022 +0200
+++ b/Dockerfile Fri May 20 13:40:04 2022 +0200
@@ -22,7 +22,7 @@
# easy to remember 'build' alias to invoke main makefile
ARG OWNDIRBASENAME=beremiz_public_dist
ENV OWNDIRBASENAME ${OWNDIRBASENAME}
-RUN echo -e '#!/bin/bash\nmake -f /home/'$UNAME'/src/'$OWNDIRBASENAME'/Makefile $*' > /usr/local/bin/build
+RUN /bin/echo -e '#!/bin/bash\nmake -f /home/'$UNAME'/src/'$OWNDIRBASENAME'/Makefile $*' > /usr/local/bin/build
RUN chmod +x /usr/local/bin/build
USER $UNAME