Fix bogus tests on rev-list output.

Fix bogus tests on rev-list output.

These tests seem to mean checking the output with expected
result, but was not doing its handrolled test helper function.

Also fix the guard to workaround wc output that have whitespace
padding, which was broken but not exposed because the test was
not testing it ;-).

Signed-off-by: Junio C Hamano <junkio@cox.net>