homebrew reverse dependencies

revdeps.py

#!/usr/bin/env python

from __future__ import print_function

import subprocess
import sys

if len(sys.argv) < 2:
    raise SystemExit('need a brew to check reverse deps for')

check_brew = sys.argv[1]

brews = subprocess.check_output(['brew', 'list', '-1']).split()
if check_brew not in brews:
    raise SystemExit('brew not actually installed, moving on')

# skip the brew itself
brews.remove(check_brew)

for brew in brews:
    try:
        deps = subprocess.check_output(['brew', 'deps', brew]).split()
    except subprocess.CalledProcessError:
        # possible issue calling brew deps due to 'fake formulas'
        continue
    if check_brew in deps:
        print('[*] {}'.format(brew))

I found the answer in 2021 for these who read this in 2027.. brew leaves
you may have to run it a few times to get rid of everything, but it works!

brew uses --installed still works in 2020. (You can use it with --recursive as necessary). Thanks @lepistone! :-)