Fix incorrect enum in Migration object and DB model

The migration object and model incorrectly mirrored the migration_type
enum from the database schema. Since the affected type (evacuation) has
never been used before this change, we can just make the swap with no
version bump.

Related to blueprint robustify-evacuation

Change-Id: If502903fecd315e24c987da6d78b73dcc1305ee3

nova/db/sqlalchemy/models.py

@@ -742,7 +742,7 @@ class Migration(BASE, NovaBase):
     # TODO(_cerberus_): enum
     status = Column(String(255))
     migration_type = Column(Enum('migration', 'resize', 'live-migration',
-                                 'evacuate'),
+                                 'evacuation'),
                             nullable=True)
     hidden = Column(Boolean, default=False)
 

nova/objects/migration.py

@@ -48,7 +48,7 @@ class Migration(base.NovaPersistentObject, base.NovaObject,
         'instance_uuid': fields.StringField(nullable=True),
         'status': fields.StringField(nullable=True),
         'migration_type': fields.EnumField(['migration', 'resize',
-                                            'live-migration', 'evacuate'],
+                                            'live-migration', 'evacuation'],
                                            nullable=False),
         'hidden': fields.BooleanField(nullable=False, default=False),
         }

nova/tests/unit/objects/test_objects.py

@@ -1099,7 +1099,7 @@ object_data = {
     'InstancePCIRequests': '1.1-fc8d179960869c9af038205a80af2541',
     'KeyPair': '1.3-bfaa2a8b148cdf11e0c72435d9dd097a',
     'KeyPairList': '1.2-60f984184dc5a8eba6e34e20cbabef04',
-    'Migration': '1.2-331b1f37d0b20b932614181b9832c860',
+    'Migration': '1.2-8784125bedcea0a9227318511904e853',
     'MigrationList': '1.2-5e79c0693d7ebe4e9ac03b5db11ab243',
     'NUMACell': '1.2-74fc993ac5c83005e76e34e8487f1c05',
     'NUMAPagesTopology': '1.0-c71d86317283266dc8364c149155e48e',