find-upstream

#!/usr/bin/env python3

'''
This script shows which local branches and github/* remote tracking branches
have already been cherry-picked into origin/master.

It will then print commands that can be used to prune these branches.  This
script makes no modifications; it is read-only.
'''

import re
import subprocess

def get_output(cmd):
  return subprocess.check_output(cmd.split(), text=True)

cmd = "git for-each-ref --format=%(refname) refs/heads/* refs/remotes/github/*"
branches = get_output(cmd)
nukable = set([])
for branch in branches.splitlines():
  print("\r"+" "*70 + f"\rChecking {branch}", end="")
  cmd=f"git log --decorate --oneline --cherry-mark --right-only origin/master...{branch}"
  output = get_output(cmd)
  if all(x.startswith('= ') for x in output.splitlines()):
    m = re.match(r'^= [0-9a-f]+ \(([^\)]*)\)', output)
    if not m:
      #print(f"No match: {output.rstrip()}")
      continue
    #print(output)
    decorations = m.group(1)
    if decorations.startswith('HEAD -> '):
      decorations = decorations[8:]
    nukable |= set(decorations.split(', '))

print("\r"+" "*70+"\rDone.")
local_branches = ' '.join(x for x in nukable if not x.startswith('github/'))
if local_branches:
  print("To prune local branches:")
  print(f"  git branch -D {local_branches}")
else:
  print("No local branches to prune.")

remote_branches = ' '.join(x[7:] for x in nukable if x.startswith('github/'))
if remote_branches:
  print("To prune remote branches:")
  print(f"  git push --delete github {remote_branches}")
else:
  print("No remote branches to prune.")