git-short-export.py

#!/usr/bin/python3

import subprocess
import shlex


def call(cmd):
    print(">>> {}".format(cmd))
    return subprocess.check_call(cmd, shell=True)


def call_output(cmd):
    print(">>> {}".format(cmd))
    return subprocess.check_output(cmd, shell=True).decode().strip()

BRANCH=u"master"
NUMBER_OF_COMMITS=200
FIRST = call_output("git rev-list origin/{}".format(BRANCH)).split()[NUMBER_OF_COMMITS]
NEW=call_output("echo 'Import commit " + FIRST + "' | git commit-tree $(git cat-file -p " + FIRST + " | awk '/tree/ {print $2}')")

print(FIRST, NEW)

call("git diff -s {} {}|cat".format(FIRST, NEW))

call("git checkout {} -B {}".format(NEW, BRANCH))

merge_map = dict()
merge_map[FIRST] = NEW

merges = call_output("git rev-list --merges --reverse {}..origin/{}".format(FIRST, BRANCH)).split()

for merge in merges:
    print("merge: ", merge)

    dev = call_output("git rev-list --parents -n 1 {} | cut -f2 -d' '".format(merge))
    branch = call_output("git rev-list --parents -n 1 {} | cut -f3 -d' '".format(merge))
    merge_base = call_output("git merge-base {} {}".format(dev, branch))
    new_merge_base = merge_map.get(merge_base, NEW)

    call("git checkout {} -f -B branch".format(new_merge_base))

    commits = call_output("git rev-list --reverse --no-merges {}..{}".format(merge_base, branch)).split()
    try:
        for commit in commits:
            call("git cherry-pick {}".format(commit))
    except subprocess.CalledProcessError:
        call("git reset --hard")
        call("git checkout -f {}".format(BRANCH))
        call("git cherry-pick -m 1 {}".format(merge))
        call("git diff -s {} HEAD|cat".format(merge))
        merge_map[merge] = call_output("git rev-list -1 HEAD")
        continue

    author = call_output("git show -s --format='%an <%ae>' {}".format(merge))
    date = call_output("git show -s --format='%ad' {}".format(merge))
    msg = call_output("git show -s --format='%B' {}".format(merge))

    call("git checkout {}".format(BRANCH))
    call("git merge --no-ff branch -m {}".format(shlex.quote(msg)))
    call("git commit --amend --author='{}' --date='{}' --no-edit".format(author, date))

    call("git diff -s {} HEAD|cat".format(merge))

    merge_map[merge] = call_output("git rev-list -1 HEAD")