Copy SemVer tags without a "v" prefix to tags with the "v" prefix, e.g. 1.2.3 -> v1.2.3.

tags2vtags.py

#!/usr/bin/env python

'''Copy SemVer tags without a "v" prefix to tags with the "v" prefix, e.g.
1.2.3 -> v1.2.3. Preserve tag author, date, & message.'''

import re
import subprocess


OLD_TAG_RE = re.compile(r'^\d+\.\d+')


def tag2vtag(tag):
    '''Copy a single tag without a leading "v" to a tag with a leading "v".'''
    dot_count = tag.count('.')
    if dot_count == 1:
        new_tag = 'v{}.0'.format(tag)
    else:
        new_tag = 'v{}'.format(tag)

    props = [
        ('name', '%cn'),
        ('email', '%ce'),
        ('date', '%ci'),
        ('ref', '%H'),
    ]
    git_show_cmd = ('git', 'show', '-s', '--pretty=format:{}'.format(
        '%n'.join(placeholder for _, placeholder in props)
    ))
    git_show = subprocess.check_output(git_show_cmd + (tag,)).splitlines()
    values = dict(zip((prop for prop, _ in props), git_show[-len(props):]))
    annotation = git_show[3:-len(props)]
    git_tag_cmd = ('git', 'tag', '-f', new_tag, values['ref'], '-m', '\n'.join(annotation))
    env = {
        'GIT_COMMITTER_NAME': values['name'],
        'GIT_COMMITTER_EMAIL': values['email'],
        'GIT_COMMITTER_DATE': values['date'],
    }
    subprocess.check_call(git_tag_cmd, env=env)


def main():
    all_tags = subprocess.check_output(('git', 'tag')).splitlines()
    old_tags = [line for line in all_tags if OLD_TAG_RE.match(line)]
    for old_tag in old_tags:
        tag2vtag(old_tag)


if __name__ == '__main__':
    main()