from contextlib import ExitStack, contextmanager
import subprocess

def command(fail = False):
    print("A")
    try:
        p = subprocess.Popen(["cat"],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
    finally:
        print("B")
    stdin, stderr = p.communicate(input="blah".encode("ascii"))
    return stdin

@contextmanager
def a():
    try:
        yield 1
    finally:
        command()

with ExitStack() as ctx:
    ctx.enter_context(a())
    ctx.enter_context(a())
    raise RuntimeError("bad")