Revert 'Remove image to local block device mapping'

https://review.openstack.org/#/c/153203/3 added check
for novaclient, removed the logic for both
--image and --block-device are added.

But actually the following valid boot command failed
due to the change here, so this patch reverted original
one and add some descriptions to avoid further removal.

nova boot test-vm --flavor m1.medium --image centos-vm-32
--nic net-id=c3f40e33-d535-4217-916b-1450b8cd3987
--block-device id=26b7b917-2794-452a-95e5-2efb2ca6e32d,bus=sata,
source=volume,bootindex=1

Change-Id: Ia29e63c72b34d3038aa591c466425e65edf5755b
Partial-Bug: #1433609
(cherry picked from commit 8679eedb83)

novaclient/tests/unit/v2/test_shell.py

@@ -292,6 +292,13 @@ class ShellTest(utils.TestCase):
                 'flavorRef': '1',
                 'name': 'some-server',
                 'block_device_mapping_v2': [
+                    {
+                        'uuid': 1,
+                        'source_type': 'image',
+                        'destination_type': 'local',
+                        'boot_index': 0,
+                        'delete_on_termination': True,
+                    },
                     {
                         'uuid': 'fake-id',
                         'source_type': 'volume',

novaclient/v2/servers.py

@@ -492,6 +492,14 @@ class ServerManager(base.BootingManagerWithFind):
             body['server']['block_device_mapping'] = \
                 self._parse_block_device_mapping(block_device_mapping)
         elif block_device_mapping_v2:
+            # Following logic can't be removed because it will leaves
+            # a valid boot with both --image and --block-device
+            # failed , see bug 1433609 for more info
+            if image:
+                bdm_dict = {'uuid': image.id, 'source_type': 'image',
+                            'destination_type': 'local', 'boot_index': 0,
+                            'delete_on_termination': True}
+                block_device_mapping_v2.insert(0, bdm_dict)
             body['server']['block_device_mapping_v2'] = block_device_mapping_v2
 
         if nics is not None: