Ensure we only use a 2.7-compatible pip for python2.7

Author: mhart

python2.7/build/Dockerfile

@@ -9,7 +9,7 @@ COPY --from=0 /var/lang /var/lang
 COPY --from=0 /var/rapid /var/rapid
 
 # Add these as a separate layer as they get updated frequently
-RUN curl --silent --show-error --retry 5 https://bootstrap.pypa.io/get-pip.py | python && \
+RUN curl --silent --show-error --retry 5 https://bootstrap.pypa.io/2.7/get-pip.py | python && \
   pip install -U 'virtualenv>=16.0.0,<20.0.0' pipenv wheel --no-cache-dir && \
   curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/1.1.4/get-poetry.py | POETRY_VERSION=1.1.4 python && \
   pip install -U awscli boto3 aws-sam-cli==0.22.0 aws-lambda-builders==0.4.0 --no-cache-dir