E122: No valid indent for long function call nested in f-string?

For the following example

class T:
    def m1(self):
        print(f"""
preamble
{some_long_func(
    some_long_arg, other_long_arg, more_long_arg)}
postamble
""")

    def m2(self):
        print(f"""
preamble
{some_long_func(
     some_long_arg, other_long_arg, more_long_arg)}
postamble
""")

there appears to be no indentation of the "long args line" that makes pycodestyle not emit a E122 ("continuation line missing indentation or outdented") for that line. (If m1 and m2 are toplevel functions and not methods, then the second form makes pycodestyle happy.)

Start by reproducing the two class-method examples and tracing the E122 check that handles continuation lines inside nested f-strings. Done means the valid indentation case no longer emits E122 while the relevant existing checks continue to pass.