submodule: add more exhaustive up-path testing

submodule: add more exhaustive up-path testing

The tests added in 63e95beb08 ("submodule: port resolve_relative_url
from shell to C", 2016-04-15) didn't do a good job of testing various
up-path invocations where the up-path would bring us beyond even the
URL in question without emitting an error.

These results look nonsensical, but it's worth exhaustively testing
them before fixing any of this code, so we can see which of these
cases were changed.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>