Tag git commits according to the author

autotag.py

#!/usr/bin/env python3

import subprocess

tags = {
    'jsmith@example.com': 'tagname'
}

fetch = subprocess.run(['git', 'fetch', 'origin', 'master'], stderr=subprocess.DEVNULL)
assert(fetch.returncode == 0)

with open('.latest-sha', 'r+') as file:
    latest_sha = file.read()
    log_from = (latest_sha+'...HEAD',) if latest_sha else ()
    log = subprocess.run(
        ['git', '--no-pager', 'log', 'origin/master', '-n', '2', '--pretty=format:%H %ae', *log_from],
        stdout=subprocess.PIPE, encoding='utf-8')
    assert(log.returncode == 0)
    if not log.stdout:
        raise SystemExit()
    for commit in log.stdout.split('\n'):
        commit_sha, user = commit.split()
        if user in tags:
            tag = subprocess.run(['git', 'tag', tags[user], commit_sha])
            push = subprocess.run(['git', 'push', 'origin', tags[user]])
            assert(push.returncode == 0)
        latest_sha = commit_sha
    file.seek(0)
    file.write(latest_sha)
    file.truncate()