I ran into the same problem today and fell back to using a docker container for building the function package. Something along the lines of the following Dockerfile would do the job (e.g. for Ubuntu 16.04):

FROM ubuntu:xenial

ENV LANG C.UTF-8

RUN apt-get update --fix-missing
RUN apt-get install -y python curl git
RUN apt-get upgrade -y
RUN curl https://bootstrap.pypa.io/get-pip.py | python2
RUN pip install python-lambda

WORKDIR /build
COPY . /build/

# run your build command
CMD lambda build --requirements requirements.txt

docker build -t mylambdacontainer .
docker run -v $(pwd)/dist:/build/dist mylambdacontainer

I mount the dist directory where the packages are created as a volume on my host machine so I can have them in the same place as I would when building natively.