TT#29456 Add more perl modules to ngcpcfg-stretch docker

The docker will be reused by ngcpcfg-unit-test job

Change-Id: I9b6ae7e08e1eb0e83306b251ab8e6dfdb90b713b

t/Dockerfile

@@ -1,5 +1,5 @@
-# DOCKER_NAME=ngcpcfg-jessie
-FROM docker.mgm.sipwise.com/sipwise-jessie:latest
+# DOCKER_NAME=ngcpcfg-stretch
+FROM docker.mgm.sipwise.com/sipwise-stretch:latest
 
 # Important! Update this no-op ENV variable when this Dockerfile
 # is updated with the current date. It will force refresh of all
@@ -15,6 +15,12 @@ RUN apt-get install --assume-yes netcat libhash-merge-perl libtemplate-perl \
   libdata-validate-ip-perl libio-interface-perl liblist-moreutils-perl libregexp-ipv6-perl
 # misc stuff for execution/debugging/devel
 RUN apt-get install --assume-yes fakeroot git lsof make strace
+# test execution; we need the backport of python3-junitxml from our own
+# repository since it's not part of Debian/stretch
+# files that get-code generates
+COPY t/sources.list.d/builddeps.list /etc/apt/sources.list.d/
+COPY t/sources.list.d/preferences /etc/apt/preferences.d/
+RUN apt-get update
 RUN apt-get install --assume-yes python3-pytest python3-junitxml
 
 RUN echo './t/testrunner' >>/root/.bash_history
@@ -27,12 +33,16 @@ WORKDIR /code/
 # When you want to build the base image from scratch
 # (jump to the next section if you don't want to build yourself!):
 #
-# % docker build --tag="ngcpcfg-jessie" -f ./t/Dockerfile .
-# % docker run --rm -i -t -v $(pwd):/code:rw ngcpcfg-jessie:latest bash
+# you need to put the proper NGCP sources at t/sources.list.d/builddeps.list
+# for instance, trunk:
+# echo "deb https://deb.sipwise.com/autobuild/ release-trunk-stretch main" > t/sources.list.d/builddeps.list
+#
+# % docker build --tag="ngcpcfg-stretch" -f ./t/Dockerfile .
+# % docker run --rm -i -t -v $(pwd):/code:rw ngcpcfg-stretch:latest bash
 #
 # Use the existing docker image:
-# % docker pull docker.mgm.sipwise.com/ngcpcfg-jessie
-# % docker run --rm -i -t -v $(pwd):/code:rw docker.mgm.sipwise.com/ngcpcfg-jessie:latest bash
+# % docker pull docker.mgm.sipwise.com/ngcpcfg-stretch
+# % docker run --rm -i -t -v $(pwd):/code:rw docker.mgm.sipwise.com/ngcpcfg-stretch:latest bash
 #
 # Inside docker (the command is in history, just press UP button):
 #   cd /code && ./t/testrunner