References: bsc#989639
When the device added is a cdrom device (/dev/sr0), don't use
"phy" as the driver name but instead use "qemu".

Index: virt-manager-4.1.0/virtinst/devices/disk.py
===================================================================
--- virt-manager-4.1.0.orig/virtinst/devices/disk.py
+++ virt-manager-4.1.0/virtinst/devices/disk.py
@@ -533,7 +533,8 @@ class DeviceDisk(Device):
         # Recommended xen defaults from here:
         # https://bugzilla.redhat.com/show_bug.cgi?id=1171550#c9
         # If type block, use name=phy. Otherwise do the same as qemu
-        if self.conn.is_xen() and self.type == self.TYPE_BLOCK:
+        if self.conn.is_xen() and self.type == self.TYPE_BLOCK and not \
+           self.is_cdrom():
             return self.DRIVER_NAME_PHY
         if self.conn.support.conn_disk_driver_name_qemu():
             return self.DRIVER_NAME_QEMU