xfstest/btrfs _require_scratch_dev_pool runs btrfsck

Here below is a simple test script. I can't understand why _require_scratch_dev_pool should check consistency on the disk ?

-------------
#! /bin/bash
# Test case 060

seq=basename $0
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"

tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

_cleanup()
{
cd /
rm -f $tmp.tmp
}

# get standard environment, filters and checks
. ./common/rc
. ./common/filter

_require_scratch_dev_pool 4

status=0
exit
-------------

./check btrfs/060

FSTYP         -- btrfs
PLATFORM      -- Linux/x86_64 OL 3.16.0-rc6+
MKFS_OPTIONS  -- /dev/sdc

MOUNT_OPTIONS -- /dev/sdc /mnt/scratch

btrfs/060 2s ... 1s
_check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent (see /usr/src/cli/xfstests/results//btrfs/060.full) <-----
Ran: btrfs/060
Passed all 1 tests

_check_btrfs_filesystem()
{
::
echo "_check_btrfs_filesystem: filesystem on $device is
inconsistent" >>$seqres.full

check
::

          test -f ${RESULT_DIR}/require_scratch && _check_scratch_fs