Debugging builds with travis ci docker images

https://stackoverflow.com/a/49019950/866759

#This is latest xenial from here: https://hub.docker.com/r/travisci/ci-sardonyx/tags/
docker run --name travis-debug -dit travisci/ci-sardonyx:packer-1564753982-0c06deb6 /sbin/init

#(Bionic below, replace the sardonyx with name from worker-info output (ubuntu-1804), 
#then and get latest tag from https://hub.docker.com/r/travisci/ci-ubuntu-1804/tags/
docker run --name travis-debug -dit travisci/ci-ubuntu-1804:packer-1566551110-e45a2919 /sbin/init

docker exec -it travis-debug bash -l

cat /etc/issue

apt update
apt install libgl1-mesa-dev mesa-utils

su - travis

#Select a venv, several python versions available
source ~/virtualenv/python2.7/bin/activate

git clone https://github.com/lavavu/LavaVu
cd LavaVu
git submodule update --init

python setup.py install
###OR
make -j5
export PYTHONPATH=${HOME}/LavaVu

cd ..
git clone --depth 1 https://github.com/lavavu/Testing
cd Testing/
export GALLIUM_DRIVER="llvmpipe";
export LV_ECHO_FAIL=1;
export LV_ARGS="-v";

#Xvfb :0 -screen 0 1600x1200x16&
#This should workaround the avfb memory leak:
Xvfb :0 -screen 0 1600x1200x16 -ac -noreset&

python runall.py

#Other options for display
apt install tigervnc-standalone-server
tigervncserver
DISPLAY=:1 ...