Erroneous capacity due to residual fibre channel path

Description
===========
There are some residual paths in /dev/disk/by-path directory
for fibre channel volume such as "/dev/disk/by-path/pci-0000
:3c:00.1-fc-0x56c92bfa002141e9-lun-3" where lun-3 is indicative
for the third volume on this node. However, the path is not a
valid path. And that leads to retrieve the same capacity as lun-3
instead of the real capacity when the other volume whose lun id
is 3 is attached to the host.

Steps to reproduce
==================
1. Assume that the node has a residual fibre channel path whose
capacity is 3G
2. Attach the other volume which has the same lun id to the instance
on the node and this volume is 5G
3. Inspect the capacity in the instance.

Expected result
===============
The new attached volume in the instance is 5G.

Actual result
=============
The capacity is 3G.

Environment
===========
the victoria branch of os-brick

Logs & Configs
==============
None