Bug 2165620

+++ This bug was initially created as a clone of Bug #2165616 +++

Description of problem:

When a QemuImgInfo object contains a format_specific value, calling
str() on it raises "AttributeError: 'list' object has no attribute 'appened'"

Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
Python 3.9.14 (main, Oct 4 2022, 17:06:42)
>>> from oslo_utils import imageutils
>>> fake_data = imageutils.QemuImgInfo()
>>> fake_data.type = 'vmdk'
>>> fake_data.format_specific = {'type': 'vmdk', 'data': {}}
>>> fake_data.format_specific['data']['create-type'] = 'monolithicSparse'
>>> str(fake_data)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".tox/py39/lib/python3.9/site-packages/oslo_utils/imageutils.py", line 103, in __str__
    lines.appened("format_specific: %s" % self.format_specific)
AttributeError: 'list' object has no attribute 'appened'
>>>

Actual results:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".tox/py39/lib/python3.9/site-packages/oslo_utils/imageutils.py", line 103, in __str__
    lines.appened("format_specific: %s" % self.format_specific)
AttributeError: 'list' object has no attribute 'appened'

Expected results:
No attributeError

Additional info:
A fix exist upstream and should be cherry-picked to OSP17.x https://opendev.org/openstack/oslo.utils/commit/d49d5944824f15d00e04e1b9c7f8c3b03b440c95