t5541: clean up truncating access log

In the second test of 't5541-http-push-smart.sh', 'no empty path components' we truncate Apache's access log by running: echo >.../access.log There are two issues with this approach: - This doesn't leave an empty file behind, like a proper truncation would, but a file with a lone newline in it. Consequently, a later test checking the log's contents must consider this improper truncation and include an empty line in the expected content. - This truncation is done in the middle of the test, because, quoting the in-code comment, "we do this [truncation] before the actual comparison to ensure the log is cleared" even when subsequent 'test_cmp' fails. Alas, this is not quite robust enough, as it is conceivable that 'git clone' fails after already having sent a request, in which case the access log would not be truncated and would leave stray log entries behind. Since there is no need for that newline at all, drop the 'echo' from the truncation and adjust the expected content accordingly. Furthermore, make sure that the truncation is performed no matter whether and how 'git clone' fails unexpectedly by specifying it as a 'test_when_finished' command. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>