fixup! gvfs-helper: create tool to fetch objects using the GVFS Protocol

We need to prevent the test case that disables writing the commit graph
from forcefully using the (now stale) commit graph.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

t/t0499-read-object.sh

@@ -53,8 +53,9 @@ test_expect_success 'no-fetch commit lookups skip object acquisition' '
 	test_write_lines "$tip" "?$parent" >expect &&
 	for helper in false true
 	do
-		GIT_TRACE2_EVENT="$PWD/no-fetch-$helper.trace" \
-		git -C no-fetch -c core.gvfs=0 -c core.commitGraph=false \
+		env GIT_TEST_COMMIT_GRAPH=0 \
+			GIT_TRACE2_EVENT="$PWD/no-fetch-$helper.trace" \
+			git -C no-fetch -c core.gvfs=0 -c core.commitGraph=false \
 			-c core.useGVFSHelper=$helper \
 			-c core.virtualizeObjects=true \
 			rev-list --missing=print HEAD >actual &&
@@ -70,7 +71,8 @@ test_expect_success 'no-fetch commit lookups still report corruption' '
 	for helper in false true
 	do
 		test_must_fail \
-			env GIT_TRACE2_EVENT="$PWD/corrupt-$helper.trace" \
+			env GIT_TEST_COMMIT_GRAPH=0 \
+			GIT_TRACE2_EVENT="$PWD/corrupt-$helper.trace" \
 			git -C no-fetch \
 			-c core.gvfs=0 -c core.commitGraph=false \
 			-c core.useGVFSHelper=$helper \