Picks a commit and puts it on a new branch

git-pick

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Usage: git pick sha branch-name --base[=origin/master]
#
# Picks a commit and puts it on a new branch that is based off "base".
# The following actions are taken:
#
# - check if branch-name does not already exist (abort if it does)
# - resolve "sha" to an absolute hash
# - git fetch
# - git checkout of branch-name based on "base"
# - git cherry-pick "sha" (using the absolute hash)
# - git checkout - (this returns us to the previous branch)
# - remove branch-name if any of the previous steps failed
#

import argparse
import subprocess
import sys


def git(*args, quiet=False):
    pipes = subprocess.Popen(['git'] + list(args),
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)

    std_out, std_err = pipes.communicate()
    std_out = std_out.decode('utf-8')
    std_err = std_err.decode('utf-8')

    if pipes.returncode != 0:
        if not quiet:
            print(std_out)
            print(std_err.strip())
        raise Exception(pipes.returncode)
    return std_out


def chop(x):
    return x[:-1] if x.endswith("\n") else x


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("sha")
    parser.add_argument("branch_name")
    parser.add_argument("--base", default="origin/master")

    args = parser.parse_args()
    args.abs_sha = chop(git("rev-parse", args.sha))

    try:
        git("diff-index", "--quiet", "HEAD", "--")
    except Exception:
        print("You have uncommitted changes")
        sys.exit(1)

    try:
        git("rev-parse", "--verify", args.branch_name, quiet=True)
    except Exception:
        pass
    else:
        print("Destination branch already exists")
        sys.exit(1)

    try:
        git("fetch")
    except Exception:
        pass

    git("branch", args.branch_name, args.base)
    git("checkout", args.branch_name)

    failed = False
    try:
        git("cherry-pick", args.abs_sha)
    except Exception:
        failed = True
        print("Sorry, cherry-pick failed")

    git("checkout", "-")

    if failed:
        git("branch", "-d", args.branch_name)