RE: file-relative-name returns "." instead of "./"

[Drew Adams]

        M-: (file-relative-name "" default-directory)
        This returns ".", but it should return "./" (IMO).

    (file-relative-name "." default-directory) returns ".".
    (file-relative-name "./" default-directory) returns "./".
    I think those are both correct.

    So which of those two cases is (file-relative-name "" default-directory)
    most like?  I am not sure.  It is not obvious that the
    current behavior is wrong.

I agree that it's not obvious.

Another logical value to return would be "". That certainly satisfies the
doc-string requirement that it is "equivalent to FILENAME when used with
that default directory as the default".