Python: Generate version number from Git commit description.

setup.py

import time

from subprocess import Popen, PIPE

try:
    describe = 'git describe --abbrev=8 --dirty'
    version = Popen(describe.split(), stdout=PIPE).communicate()[0].strip()
except:
    version = None
else:
    if version.endswith('dirty'):
        version = version[:-5] + time.strftime('%Y%m%d%H%M')

    with open('app/__version__.py', 'w') as f:
        f.write('# this file is autogenerated by setup.py\n')
        f.write('version = "{0}"\n'.format(version))

try:
    from app import __version__
    version = __version__.version
except ImportError:
    version = 'unknown'