** Using WeBWorK **

I am on a MacBook Pro, El Capitan. I am following the instructions at:

https://github.com/openwebwork/webwork2/wiki/Docker-newbie-instructions

for getting WeBWorK workng with Docker. I seem to have gotten Docker installed fine, and I can see nginx at localhost. I cloned WeBWorK components into a webwork_docker folder.

When I do the "docker-compose up", everything appears to succeed except it ends with this error:

ERROR: Service 'app' failed to build: The command '/bin/sh -c WEBWORK_VERSION=`cat /tmp/VERSION|sed -n 's/.*\(develop\)'\'';/\1/p' && cat /tmp/VERSION|sed -n 's/.*\([0-9]\.[0-9]*\)'\'';/PG\-\1/p'` && curl -fSL https://github.com/openwebwork/pg/archive/${WEBWORK_VERSION}.tar.gz -o /tmp/${WEBWORK_VERSION}.tar.gz && tar xzf /tmp/${WEBWORK_VERSION}.tar.gz && mv pg-${WEBWORK_VERSION} $APP_ROOT/pg && rm /tmp/${WEBWORK_VERSION}.tar.gz && curl -fSL https://github.com/openwebwork/webwork-open-problem-library/archive/master.tar.gz -o /tmp/opl.tar.gz && tar xzf /tmp/opl.tar.gz && mv webwork-open-problem-library-master $APP_ROOT/libraries/webwork-open-problem-library && rm /tmp/opl.tar.gz && curl -fSL https://github.com/mathjax/MathJax/archive/master.tar.gz -o /tmp/mathjax.tar.gz && tar xzf /tmp/mathjax.tar.gz && mv MathJax-master $APP_ROOT/MathJax && rm /tmp/mathjax.tar.gz && rm /tmp/VERSION' returned a non-zero code: 22

Does anyone have advice? I know that work is underway to get Docker issues ironed out in the 2.14 pre-release branch. It appears I may be experiencing one such issue. But also I'd like to help if I can.