Revert "Truncate encoded instance message to 255"

This reverts commit bd9c32289f.

UTF-8 character bytes size varies from 1 to 6. If truncating a long
bytes string to 255, the last character may be cut in the middle,
so that UnicodeDecodeError will occur when converting it back to
unicode. Need to revert this code change and make a new patch.

Related-Bug: 1389102

Change-Id: Ie439cffe11d657e77397c9070a3923a61f68a678

nova/compute/utils.py

@@ -19,7 +19,6 @@ import string
 import traceback
 
 from oslo.config import cfg
-from oslo.utils import encodeutils
 
 from nova import block_device
 from nova.compute import flavors
@@ -65,7 +64,7 @@ def exception_to_dict(fault):
     # NOTE(dripton) The message field in the database is limited to 255 chars.
     # MySQL silently truncates overly long messages, but PostgreSQL throws an
     # error if we don't truncate it.
-    u_message = encodeutils.safe_decode(encodeutils.safe_encode(message)[:255])
+    u_message = unicode(message)[:255]
 
     fault_dict = dict(exception=fault)
     fault_dict["message"] = u_message

nova/tests/unit/compute/test_compute_utils.py

@@ -22,7 +22,6 @@ import string
 import mock
 from oslo.config import cfg
 from oslo.serialization import jsonutils
-from oslo.utils import encodeutils
 from oslo.utils import importutils
 import six
 import testtools
@@ -826,13 +825,3 @@ class ComputeUtilsGetRebootTypes(test.TestCase):
     def test_get_reboot_not_running_hard(self):
         reboot_type = compute_utils.get_reboot_type('foo', 'bar')
         self.assertEqual(reboot_type, 'HARD')
-
-
-class ComputeUtilsTestCase(test.NoDBTestCase):
-    def test_exception_to_dict_with_long_message(self):
-        # Generate Russian byte message whose length is 300
-        msg = encodeutils.safe_decode(' \xd0\xb2' * 100)
-        exc = exception.NovaException(message=msg)
-        fault_dict = compute_utils.exception_to_dict(exc)
-        byte_message = encodeutils.safe_encode(fault_dict["message"])
-        self.assertEqual(255, len(byte_message))