Just use 'exception_to_unicode' to handle exception to string
Just use 'exception_to_unicode' to handle exception to string

This functions primary purposes is to try to safely convert
an exception object into a unicode string, and handle the errors
that may occur due to that, so we can just use that instead.

Change-Id: I0f7fa0b98512fe22325281adf4bd0e1fe6087e98

openstack/oslo.utils