It just happens so that when GIT_EXEC_PATH points to a compiled checkout
of git.git it contains "git". Since this is not true in general make
test-lib check for "git-init" which is always in GIT_EXEC_PATH.
Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>