Before applying the patch, in a new pool (during the CH8 update process to XCP8), when moving any VM to the updated host I received the error below.
After installing the patch on the master host and restarting the toolstack on the host master and the source host, we no longer notice error, with the migrate process successfully completing.
The error condition was the failed shutdown of the VM in the live migrate process. So I think the patch made available actually solves the problem in question. (for VMs with and without network interfaces)
Nov 30 12:54:48 SECH82 xapi: [error|SECH82|946189 ||backtrace] Async.VM.pool_migrate R:29b4b31d74de failed with exception Server_error(INTERNAL_ERROR, [ xenopsd internal error: Device_common.QMP_Error(135, "{\"error\":{\"class\":\"GenericError\",\"desc\":\"Unable to open /dev/fdset/0: No such file or directory\",\"data\":{}},\"id\":\"qmp-000029-135\"}") ])
Nov 30 12:54:48 SECH82 xapi: [error|SECH82|946189 ||backtrace] Raised Server_error(INTERNAL_ERROR, [ xenopsd internal error: Device_common.QMP_Error(135, "{\"error\":{\"class\":\"GenericError\",\"desc\":\"Unable to open /dev/fdset/0: No such file or directory\",\"data\":{}},\"id\":\"qmp-000029-135\"}") ])
Nov 30 12:54:48 SECH82 xapi: [error|SECH82|946189 ||backtrace] 1/1 xapi @ SECH82 Raised at file (Thread 946189 has no backtrace table. Was with_backtraces called?, line 0
Nov 30 12:54:48 SECH82 xapi: [error|SECH82|946189 ||backtrace]