E115, Expected an indented block (comment), not detected

According to PEP-8 on block styles, it merely says:

Block comments generally apply to some (or all) code that follows them, and are indented to the same level as that code. 

The existing E115 is supposed to check this. However, the following test code does not trigger it:

class SomeBase:
    pass


class SomeClass(SomeBase):

    def method(self, arg):
        if not arg:
            return "arg is false"
# Will return true on truthy
        return "arg is true"

I think that should be caught. It does cause a problem with building documentation with Sphinx that includes source code snippets. The generated RST has the de-dented line signalling the end of the code block.

Thanks!

Start by reproducing the provided Python snippet and trace the E115 checker in pycodestyle's single Python source file. Add or update a regression test for the de-dented comment case, and confirm that it is reported without incorrectly flagging valid block comments.