
In the current testing setup for tree_search(), the case for non-existent key is not exercised. Improve this by adding a test-case for the same. Mentored-by: Patrick Steinhardt <ps@pks.im> Mentored-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>