git-bumptip

#!/usr/bin/env python

import argparse
import os
import re
import subprocess
import sys

parser = argparse.ArgumentParser(description='Check out the next version available of a given branch',
                                 epilog="Also consider used version numbers that are not in local branches but only in a remote branch. It refuses to bump versions of the 'master' branch since this is usually a mistake.")

parser.add_argument('-n', '--dry-run',
                    action='store_true', default=False,
                    help="dry-run, no action is actually taken")
args = parser.parse_args()


def sh(cmd):
    try:
        return subprocess.check_output(cmd, stderr=subprocess.STDOUT).decode('utf-8')
    except subprocess.CalledProcessError as err:
        sys.stderr.write(err.output.decode('utf-8'))
        sys.exit(1)


def split_version(branch):
    m = re.match("^(.*)-v(\d+)$", branch)
    if m is None:
        return branch, 1
    return m.group(1), int(m.group(2))

branch = sh(["git", "rev-parse", "--abbrev-ref", "HEAD"]).rstrip()
name, current = split_version(branch)

if name == "master":
    sys.exit("ERROR: won't version the 'master' branch")

latest = current
latest_branch = branch

branches = sh(["git", "for-each-ref", "--format=%(refname:short)"]).rstrip().split("\n")
for b in branches:
    m = re.match("(|.*/)%s(-v(\d+))?$" % name, b)
    if m is None:
        continue
    _, v = split_version(b)
    if v > latest:
        latest = v
        latest_branch = b

print("Latest branch is '%s'" % latest_branch)
next_version = latest + 1
checkout = ["git", "checkout", "-b", "%s-v%d" % (name, next_version)]

if args.dry_run:
    print("# " + " ".join(checkout))
else:
    sys.stdout.write(sh(checkout))