t7800: improve test descriptions with empty arguments
Some of the tests in t7800 are executed repeatedly in a loop with
different arguments. To distinguish these tests, the value of that
variable is rendered into the test title. But given that one of the
values is the empty string, it results in a somewhat awkward test name:
difftool ignores exit code
Improve this by printing "without options" in case the value is empty.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>