qtivi is downloading python packages on every build in CI

According to this snippet of logs (http://coin/coin/api/results/qt/qtivi/b0a66cb6a718f8d9acfb93fb876b30a07050f467/LinuxUbuntu_16_04x86_64LinuxUbuntu_16_04x86_64GCCqtci-linux-Ubuntu-16.04-x86_64-2-bd464cNoWidgets_ForceDebugInfo/dd028d7efd8deffac35ca303e8dd9c86c3125ced/build_1519110895/log.txt.gz):

New python executable in /home/qt/work/qt/qtivi/src/tools/ivigenerator/qtivi_qface_virtualenv/bin/python3
Also creating executable in /home/qt/work/qt/qtivi/src/tools/ivigenerator/qtivi_qface_virtualenv/bin/python
Installing setuptools, pkg_resources, pip, wheel...
Complete output from command /home/qt/work/qt/qti...rtualenv/bin/python3 - setuptools pkg_resources pip wheel:
Collecting setuptools
Downloading setuptools-38.5.1-py2.py3-none-any.whl (489kB)
Collecting pkg_resources
Collecting pip
Downloading pip-9.0.1-py2.py3-none-any.whl (1.3MB)

QtIVI tries to re-download packages on every build. That is not only slow and against of policies but also flaky. Please try to provision the images. You can use something like that, during provisioning:

pip3 wheel --wheel-dir $HOME/wheel -r ${BASH_SOURCE%/*}/../common/requirements.txt

and then inside the build system:

$(PYTHON_PIP) install --find-links=$(HOME)/wheel -r