Record pip version in our python image builds

This is useful for debugging when pip does updates and we need to be
sure that we ran with a new (or old) version of pip.

Change-Id: I556bb68e255ee0bdbcbd2c72dc537e2a6c7d64b6

docker/python-base/Dockerfile

@@ -31,7 +31,7 @@ RUN apt-get update \
 
 # Upgrade pip to fix wheel cache for locally built wheels.
 # See https://github.com/pypa/pip/issues/6852
-RUN pip install -U pip
+RUN pip install -U pip && pip --version
 
 # Undo debian changes to openssl.cnf that are too aggressive
 COPY openssl.cnf /etc/ssl/openssl.cnf

docker/python-builder/Dockerfile

@@ -45,4 +45,4 @@ RUN dpkg -i /tmp/python3-dev_4.0.0_all.deb \
 
 # Upgrade pip to fix wheel cache for locally built wheels
 # See https://github.com/pypa/pip/issues/6852
-RUN pip install -U pip
+RUN pip install -U pip && pip --version

docker/python-builder/scripts/assemble

@@ -91,6 +91,8 @@ done
 python3 -m venv /tmp/venv
 /tmp/venv/bin/pip install -U pip wheel build
 
+/tmp/venv/bin/pip --version
+
 # If there is an upper-constraints.txt file in the source tree,
 # use it in the pip commands.
 if [ -f /tmp/src/upper-constraints.txt ] ; then

docker/python-builder/scripts/install-from-bindep

@@ -24,6 +24,8 @@ if [ -f /output/upper-constraints.txt ] ; then
     CONSTRAINTS="-c /output/upper-constraints.txt"
 fi
 
+pip --version
+
 # If a requirements.txt file exists,
 # install it directly so that people can use git url syntax
 # to do things like pick up patched but unreleased versions