Merge pull request #582 from hashicorp/fix/reattach-cdrom

fix: keep lowest-numbered cd-roms

Author: kp2099

builder/vsphere/driver/vm_cdrom.go

@@ -100,7 +100,11 @@ func (vm *VirtualMachineDriver) RemoveNCdroms(n int) error {
 		return fmt.Errorf("invalid number: n must be between 0 and %d", len(cdroms))
 	}
 
-	cdroms = cdroms[:n]
+	// Remove up to n CD-ROMs from the end of the list.
+	// For example, removing from the end preserves lower-numbered device slots, which
+	// prevents IDE controller errors where a slave device exists without a primary
+	// (master) device.
+	cdroms = cdroms[len(cdroms)-n:]
 	if err = vm.RemoveDevice(true, cdroms...); err != nil {
 		return err
 	}

builder/vsphere/driver/vm_mock.go

@@ -289,7 +289,7 @@ func (vm *VirtualMachineMock) RemoveNCdroms(nCdroms int) error {
 	if nCdroms == 0 {
 		return nil
 	}
-	vm.CdromDevicesList = vm.CdromDevicesList[:nCdroms]
+	vm.CdromDevicesList = vm.CdromDevicesList[len(vm.CdromDevicesList)-nCdroms:]
 	return vm.RemoveNCdromsErr
 }