The build script doesn't shutdown the guest VMs properly,
which results in filesystem corruption and guest boot
failures sooner or later.

Use the --snapshot to run builds on a snapshot,
That way killing the VM doesn't corrupt the base image.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 tests/vm/Makefile.include | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/vm/Makefile.include b/tests/vm/Makefile.include
index 992d823f6bd2..d628e0a986f6 100644
--- a/tests/vm/Makefile.include
+++ b/tests/vm/Makefile.include
@@ -53,6 +53,7 @@ vm-build-%: $(IMAGES_DIR)/%.img
 		$(if $(V),--verbose) \
 		--image "$<" \
 		$(if $(BUILD_TARGET),--build-target $(BUILD_TARGET)) \
+		--snapshot \
 		--build-qemu $(SRC_PATH) -- \
 		$(if $(TARGET_LIST),--target-list=$(TARGET_LIST)) \
 		$(if $(EXTRA_CONFIGURE_OPTS),$(EXTRA_CONFIGURE_OPTS)), \
-- 
2.18.1