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!
Tim Abbott
Steven Oud
Tim Abbott
Leo Franchi
Zev Benjamin