push to a remote checked out repository (by pushing into a temporary branch and then ssh-ing to the repository and performing the merge)

git-copush

#!/usr/bin/env python
import argparse
import re
import subprocess
import sys
import uuid

url_rex = re.compile(
    "^(?P<user>.*?)@(?P<host>.*?):(?:(?P<port>[0-9]*?))?(?P<path>.*?/.*?)$"
)
refspec_match = re.compile("^(?P<noff>[+]?)(?P<src>[^:]+):(?P<dst>[^:]+)$").match


def build_ssh_url(urldict):
    port_str = ":" + str(urldict["port"]) if urldict["port"] else ""
    return "{username}@{host}{port_str}".format(
        username=urldict["user"], host=urldict["host"], port_str=port_str
    )


def get_url(url_or_origin):
    print((">%r<" % (url_or_origin,)))
    match = url_rex.match(url_or_origin)
    if match:
        return None, url_or_origin, match.groupdict()
    return (url_or_origin,) + get_url(
            subprocess.check_output(["git", "remote", "get-url", url_or_origin]).decode("utf-8").strip()
        )[1:]


if __name__ == "__main__":
    TMP_BRANCH = "COPUSH_TMP_" + uuid.uuid4().hex
    print((repr(sys.argv)))
    parser = argparse.ArgumentParser(
        epilog=f"{sys.argv[0]} REMOTE local_branch:remote_branch"
    )
    parser.add_argument("remote", help="remote.")
    parser.add_argument("refspec", help="refspec")
    try:
        args = parser.parse_args(sys.argv[1:])
    except SystemExit as e:
        if e.code != 0:
            parser.print_help()
        raise


    remote, url, urldict = get_url(args.remote)
    print(("remote:", remote))
    refspecdict = refspec_match(args.refspec).groupdict()

    print(f"Remote branch: {TMP_BRANCH}")
    print(("urldict", urldict))
    print(("refspecdict", refspecdict))
    print("-------------------")
    assert not refspecdict["noff"]  # non-fast-forward not yet supported

    cmd = ["git", "push", url, "%s:%s" % (refspecdict["src"], TMP_BRANCH)]
    print((repr(cmd)))
    result = subprocess.check_call(cmd)

    sshcmd = ("cd {path}; "
              "if [ $(git symbolic-ref -q HEAD --short) = '{dst}' ]; then "  # test whether the branch {dst} is currently checked out (HEAD)
              "git merge {tmp_branch} --ff-only --no-commit; "  # if it is checked out, perform a non-merging merge (fast-forward) without merge-commits (--no-commit)
              "else "
              "git fetch . {tmp_branch}:{dst}; "  # if it isn't checked out, we don't need to merge but just fetch.
              "fi; "
              "git branch -D {tmp_branch}"  # delete the temporary COPUSH branch.
              ).format(
        path=urldict["path"], tmp_branch=TMP_BRANCH, dst=refspecdict["dst"]
    )
    cmd = ["ssh", build_ssh_url(urldict), sshcmd]
    result = subprocess.check_call(cmd)

    if remote is not None:
        subprocess.check_call(["git", "fetch", remote])