fix rebuild sha1 not string error

fixes bug #889164
The sha1() parameter is converted to a string
before calling the funcion.

(cherry picked from commit 17ae2d2)

Change-Id: I9cb6ff43c106c214e027d3bdacb795b4b0269f94

nova/tests/test_libvirt.py

@@ -926,7 +926,10 @@ def fake_none(self, instance):
             return
 
         self.create_fake_libvirt_mock()
-        instance = db.instance_create(self.context, self.test_instance)
+
+        instance_ref = self.test_instance
+        instance_ref['image_ref'] = 123456  # we send an int to test sha1 call
+        instance = db.instance_create(self.context, instance_ref)
 
         # Start test
         self.mox.ReplayAll()
@@ -939,7 +942,10 @@ def fake_none(self, instance):
         try:
             conn.spawn(self.context, instance, network_info)
         except Exception, e:
-            count = (0 <= str(e.message).find('Unexpected method call'))
+            # assert that no exception is raised due to sha1 receiving an int
+            self.assertEqual(-1, str(e).find('must be string or buffer'
+                                             ', not int'))
+            count = (0 <= str(e).find('Unexpected method call'))
 
         shutil.rmtree(os.path.join(FLAGS.instances_path, instance.name))
         shutil.rmtree(os.path.join(FLAGS.instances_path, '_base'))

nova/virt/libvirt/connection.py

@@ -866,7 +866,7 @@ def basepath(fname='', suffix=suffix):
                                   user_id=inst['user_id'],
                                   project_id=inst['project_id'])
 
-        root_fname = hashlib.sha1(disk_images['image_id']).hexdigest()
+        root_fname = hashlib.sha1(str(disk_images['image_id'])).hexdigest()
         size = FLAGS.minimum_root_size
 
         inst_type_id = inst['instance_type_id']