`npm install` fails nondeterministically occasionally, and this makes
such failures likely to be automatically resolved in most cases by
simple retrying.
Factor out the code in tools/provision.py which installs a python2
and python3 venv into a module (tools/setup/setup_venvs.py) which
can also be used as a script.
Twisted is not python 3 compatible. So for now create a python2
venv and install twisted in it when running provision.py in python3
mode and use twisted from the python2 venv.
tools/provision.py: Create directory var/uploads.
zproject/local_settings_template.py: Update Upload dir to var/uploads.
zproject/dev_settings.py: Update upload dir to var/uploads.
The purpose of this is to move a lot of the log and other generated
files used by the Zulip development environment into a consistent
hierarchy.
We also need to create this in tools/build-release-tarball as well,
since that runs a development environment out of a temporary
directory.
When provision.py is run using python 2, retain original behavior
of creating a python 2 venv using requirements/py2_dev.txt and
creating a python 3 venv using requirements/mypy.txt.
When provision.py is run using python 3, install a single python 3
venv with requirements/py3_dev.txt.
Tim Abbott
Eklavya Sharma
Taranjeet Singh