repo2docker: repo2docker hangs on local install

Running latest repo2docker fresh from pypi:

FROM buildpack-deps:artful

# Set up locales properly
RUN apt-get update && \
    apt-get install --yes --no-install-recommends locales && \
    apt-get purge && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

RUN echo "en_US.UTF-8 UTF-8" > /etc/locale.gen && \
    locale-gen

ENV LC_ALL en_US.UTF-8
ENV LANG en_US.UTF-8
ENV LANGUAGE en_US.UTF-8

# Use bash as default shell, rather than sh
ENV SHELL /bin/bash

# Set up user
ARG NB_USER
ARG NB_UID
ENV USER ${NB_USER}
ENV HOME /home/${NB_USER}

RUN adduser --disabled-password \
    --gecos "Default user" \
    --uid ${NB_UID} \
    ${NB_USER}
WORKDIR ${HOME}

RUN apt-get update && \
    apt-get install --yes --no-install-recommends \
       less \
       npm \
       && apt-get purge && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

RUN apt-get update && \
    apt-get install --yes \
       python3 \
       python3-dev \
       python3-venv \
       && apt-get purge && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*
EXPOSE 8888

# Almost all environment variables
ENV APP_BASE /srv
ENV VENV_PATH ${APP_BASE}/venv
ENV NB_PYTHON_PREFIX ${VENV_PATH}
# Special case PATH
ENV PATH ${VENV_PATH}/bin:${PATH}
# If scripts required during build are present, copy them

COPY python/requirements.frozen.txt /tmp/requirements.frozen.txt
RUN mkdir -p ${VENV_PATH} && \
chown -R ${NB_USER}:${NB_USER} ${VENV_PATH}

USER ${NB_USER}
RUN python3 -m venv ${VENV_PATH}

RUN pip install --no-cache-dir -r /tmp/requirements.frozen.txt && \
jupyter nbextension enable --py widgetsnbextension --sys-prefix && \
jupyter serverextension enable --py jupyterlab --sys-prefix && \
jupyter serverextension enable nteract_on_jupyter --sys-prefix



# Copy and chown stuff. This doubles the size of the repo, because
# you can't actually copy as USER, only as root! Thanks, Docker!
USER root
COPY src/ ${HOME}
RUN chown -R ${NB_USER}:${NB_USER} ${HOME}

# Run assemble scripts! These will actually build the specification
# in the repository into the image.
RUN apt-get update && \
apt-get install --yes --no-install-recommends pandoc texlive-latex-base texlive-latex-recommended texlive-science texlive-latex-extra texlive-fonts-recommended dvipng ghostscript && \
apt-get purge && \
apt-get clean && \
rm -rf /var/lib/apt/lists/*

USER ${NB_USER}
RUN pip3 install --no-cache-dir -r "requirements.txt"


# Container image Labels!
# Put these at the end, since we don't want to rebuild everything
# when these change! Did I mention I hate Dockerfile cache semantics?


# We always want containers to run as non-root
USER ${NB_USER}

RUN ./postBuild

Using PythonBuildPack builder
Step 1/33 : FROM buildpack-deps:artful
 ---> 15aabadeaee6
Step 2/33 : RUN apt-get update &&     apt-get install --yes --no-install-recommends locales &&     apt-get purge &&     apt-get clean &&     rm -rf /var/lib/apt/lists/*
 ---> Using cache
 ---> a503cac6c9ac
Step 3/33 : RUN echo "en_US.UTF-8 UTF-8" > /etc/locale.gen &&     locale-gen
 ---> Using cache
 ---> 2f62ac8d042a
Step 4/33 : ENV LC_ALL en_US.UTF-8
 ---> Using cache
 ---> 5246ca660498
Step 5/33 : ENV LANG en_US.UTF-8
 ---> Using cache
 ---> 46d5ee905d85
Step 6/33 : ENV LANGUAGE en_US.UTF-8
 ---> Using cache
 ---> 25ca381c1ccb
Step 7/33 : ENV SHELL /bin/bash
 ---> Using cache
 ---> 2f3e4d95e5a6
Step 8/33 : ARG NB_USER
 ---> Using cache
 ---> d0da0c76273f
Step 9/33 : ARG NB_UID
 ---> Using cache
 ---> 23f9d9d773c6
Step 10/33 : ENV USER ${NB_USER}
 ---> Using cache
 ---> 996af037e629
Step 11/33 : ENV HOME /home/${NB_USER}
 ---> Using cache
 ---> 09634520cc8c
Step 12/33 : RUN adduser --disabled-password     --gecos "Default user"     --uid ${NB_UID}     ${NB_USER}
 ---> Running in 14bb574a0353
Adding user `ajh59' ...
Adding new group `ajh59' (494230618) ...
Adding new user `ajh59' (494230618) with group `ajh59' ...
Creating home directory `/home/ajh59' ...
Copying files from `/etc/skel' ...

and then it just hangs. It also seems to break my docker install by using up all memory, though I can’t see where. I wonder if the copy could be infinitely stuck somehow?