umount wrong mount path

[Einst Crazy]

when have run the stack with ceph before. the stack.sh will mount to /var/lib/ceph/. But the next time we run the stack.sh, it failed to umount the path. for it have wrong path.

error messages:

++functions:create_disk:712 local node_number
++functions:create_disk:713 local disk_image=/var/lib/ceph/drives/images/ceph.img
++functions:create_disk:714 local storage_data_dir=/var/lib/ceph
++functions:create_disk:715 local loopback_disk_size=24G
++functions:create_disk:718 [[ -e /var/lib/ceph/drives/images/ceph.img ]]
++functions:create_disk:719 egrep -q /var/lib/ceph /proc/mounts
++functions:create_disk:720 sudo umount /var/lib/ceph/drives/sdb1
umount: /var/lib/ceph/drives/sdb1: mountpoint not found
+functions:create_disk:1 exit_trap
+./stack.sh:exit_trap:515 local r=32
++./stack.sh:exit_trap:516 jobs -p
+./stack.sh:exit_trap:516 jobs=
+./stack.sh:exit_trap:519 [[ -n '' ]]
+./stack.sh:exit_trap:525 '[' -f '' ']'
+./stack.sh:exit_trap:530 kill_spinner
+./stack.sh:kill_spinner:425 '[' '!' -z '' ']'
+./stack.sh:exit_trap:532 [[ 32 -ne 0 ]]
+./stack.sh:exit_trap:533 echo 'Error on exit'
Error on exit
+./stack.sh:exit_trap:535 type -p generate-subunit
+./stack.sh:exit_trap:536 generate-subunit 1519449818 181 fail
+./stack.sh:exit_trap:538 [[ -z /opt/stack/logs ]]
+./stack.sh:exit_trap:541 /home/centos/devstack/tools/worlddump.py -d /opt/stack/logs
World dumping... see /opt/stack/logs/worlddump-2018-02-24-052640.txt for details
+./stack.sh:exit_trap:550 exit 32

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/547750

[OpenStack Infra (hudson-openstack)]

Change abandoned by Einst Crazy ([e-mail]) on branch: master
Review: https://review.openstack.org/547750
Reason: conflict with Ie9fe81c820c485dab9f049cf5a81c02424925728