iotests: 018: Use TEST_IMG override instead of "mv"

Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 1450752561-9300-2-git-send-email-famz@redhat.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

tests/qemu-iotests/018

@@ -66,8 +66,8 @@ _check_test_img
 echo "Creating test image with backing file"
 echo
 
-TEST_IMG=$TEST_IMG_SAVE
-_make_test_img -b "$TEST_IMG.base" 6G
+TEST_IMG="$TEST_IMG_SAVE.orig"
+_make_test_img -b "$TEST_IMG_SAVE.base" 6G
 
 echo "Filling test image"
 echo
@@ -81,8 +81,8 @@ for offset in $TEST_OFFSETS; do
 done
 _check_test_img
 
-mv "$TEST_IMG" "$TEST_IMG.orig"
-$QEMU_IMG convert -O $IMGFMT "$TEST_IMG.orig" "$TEST_IMG"
+TEST_IMG="$TEST_IMG_SAVE"
+$QEMU_IMG convert -f $IMGFMT -O $IMGFMT "$TEST_IMG.orig" "$TEST_IMG"
 
 echo "Reading"
 echo

tests/qemu-iotests/018.out

@@ -269,7 +269,7 @@ wrote 65536/65536 bytes at offset 4295032832
 No errors were found on the image.
 Creating test image with backing file
 
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=6442450944 backing_file=TEST_DIR/t.IMGFMT.base
+Formatting 'TEST_DIR/t.IMGFMT.orig', fmt=IMGFMT size=6442450944 backing_file=TEST_DIR/t.IMGFMT.base
 Filling test image
 
 === IO: pattern 1