http-backend fatal error message on shallow clone

From: Eric Wong <e@80x24.org>
Date: Jun 21, 2016, 11:23 UTC
Message-ID: <20160621112303.GA21973@dcvr.yhbt.net>

I noticed "fatal: The remote end hung up unexpectedly" in server logs from shallow clones. Totally reproducible in the test cases, too. The following change shows it:

diff --git a/t/t5561-http-backend.sh b/t/t5561-http-backend.sh
index 90e0d6f..cfa55ce 100755
--- a/t/t5561-http-backend.sh
+++ b/t/t5561-http-backend.sh
@@ -132,5 +132,11 @@ test_expect_success 'server request log matches test results' '
 	test_cmp exp act
 '
 
+test_expect_success 'shallow clone' '
+	config http.uploadpack true &&
+	git clone --depth=1 "$HTTPD_URL/smart/repo.git" shallow &&
+	tail "$HTTPD_ROOT_PATH"/error.log | grep fatal
+'
+
 stop_httpd
 test_done


And the last test ends like this:

expecting success: 
	config http.uploadpack true &&
	git clone --depth=1 "$HTTPD_URL/smart/repo.git" shallow &&
	tail "$HTTPD_ROOT_PATH"/error.log | grep fatal

Cloning into 'shallow'...
[Tue Jun 21 11:07:41.391269 2016] [cgi:error] [pid 21589] [client 127.0.0.1:37518] AH01215: fatal: The remote end hung up unexpectedly
ok 15 - shallow clone

It doesn't show above, but I think http-backend exits
with a non-zero status, too, which might cause some CGI
implementations to complain or break.

Not sure if it's just a corner case that wasn't tested
or something else, but the clone itself seems successful...