Invalid code after indented `# fmt: off`

[ambv]

Input:

def x():
    # fmt: off
    return

def y():
    return

Invalid code produced:

def x():
    # fmt: off
    return

    def y():
        return

[devxpy]

Is this supposed to work?

It leaves the file unchanged, but I would expect something like this

in.py

# fmt: off
def x():
    return pow(
2,3)
    # fmt: on
    return pow(
2,3
)

out.py

# fmt: off
def x():
    return pow(
2,3)
    # fmt: on
    return pow(2,3)

---

~ ) cat test.py 
# fmt: off
def x():
    return pow(
2,3)
    # fmt: on
    return pow(
2,3
)
~ ) black test.py
All done! ✨ 🍰 ✨
1 file left unchanged.
~ ) cat test.py 
# fmt: off
def x():
    return pow(
2,3)
    # fmt: on
    return pow(
2,3
)