t7401: add a NEEDSWORK

t7401: add a NEEDSWORK

Add a NEEDSWORK regarding the outdated syntax and working of the test,
which may need to be improved to obtain better and desired results.

While at it, change the word 'test' to 'test script' in the test
description to avoid ambiguity.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Kaartic Sivaraam <kaartic.sivaraam@gmail.com>
Helped-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Shourya Shukla <shouryashukla.oo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>