t2016: add a NEEDSWORK about the PERL prerequisite

Since the builtin add-p is used when $GIT_TEST_ADD_I_USE_BUILTIN is
given, we should replace the PERL prerequisite with an ADD_I
prerequisite which first checks if $GIT_TEST_ADD_I_USE_BUILTIN is
defined before checking PERL.[0] Mark this in a NEEDSWORK so that it can
be addressed at a later time.

[0]: https://lore.kernel.org/git/xmqqsgat7ttf.fsf@gitster.c.googlers.com/

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t2016-checkout-patch.sh

@@ -18,6 +18,10 @@ test_expect_success PERL 'setup' '
 
 # note: bar sorts before dir/foo, so the first 'n' is always to skip 'bar'
 
+# NEEDSWORK: Since the builtin add-p is used when $GIT_TEST_ADD_I_USE_BUILTIN
+# is given, we should replace the PERL prerequisite with an ADD_I prerequisite
+# which first checks if $GIT_TEST_ADD_I_USE_BUILTIN is defined before checking
+# PERL.
 test_expect_success PERL 'saying "n" does nothing' '
 	set_and_save_state dir/foo work head &&
 	test_write_lines n n | git checkout -p &&