Allow test_commit failures in loop iterations before the last one to
cause the test assertion to fail.
More importantly, avoiding these loops makes the test a little
simpler to read and decreases the vertical screen footprint of
the setup test assertion by one line.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>