<bug>[storage-device]: fix add multipath blacklist

'multipath -l -v1' execution will fail when the device is added to multipath blacklist

 Resolves: ZSTAC-49061

 Change-Id: 6e6529eb57034973b26bb33a955976ae

Author: shan.wu

kvmagent/kvmagent/plugins/storage_device.py

@@ -313,7 +313,9 @@ def refresh_mpath(disks_by_path):
             devpaths = [os.path.realpath(os.path.join("/dev/disk/by-path", s)) for s in disks_by_path]
             mpaths = set()
             for devpath in devpaths:
-                if devpath: mpaths.add(shell.call("multipath -l -v1 "+devpath).strip())
+                r, o = bash.bash_ro("multipath -l -v1 %s" % devpath)
+                if r == 0 and o.strip() != "":
+                    mpaths.add(o.strip())
             for mpath in mpaths:
                 if mpath: shell.run("multipathd resize map "+mpath)