A common issue when doing a Zulip upgrade is trying to pass
upgrade-zulip a tarball path under /root, which doesn't work because
the Zulip user doesn't have permission to read the tarball. We
could fix this by just unpacking the tarballs as root, but it seemed
like a nicer approach would be to archive the release tarballs
somewhere readable by the Zulip user (/home/zulip/archives) and unpack
them from there.
Fixes#208.
The point of the lock is to prevent two deployments happening at the
same time and racing with each other, not to prevent doing any future
deployments after an error happens (which is what the current
implementation does in practice).
Addresses part of #208.
The #! line processing interpreted the argument to pass to `env` as
"python2.7 -u", which obviously isn't a real program.
We fix this by setting the PYTHONUNBUFFERED environment variable
inside the program, which has the same effect.
Thanks to Dan Fedele for the bug report and suggested solution!