Before this change using an anchor/alias in !j2-yaml resulted in an
exception, even if retain_anchors was set to True:
> File "(...)/jenkins-job-builder/.tox/py38/lib/python3.8/site-packages/yaml/composer.py", line 68, in compose_node
> raise ComposerError(None, None, "found undefined alias %r"
> yaml.composer.ComposerError: found undefined alias '<alias-name-xxx>'
The reason was that LateYamlLoader.get_object_to_format() was calling
load() without retain_anchors=True so effectively it was resetting
anchors during deep formatting...
From now on yaml.load() is called directly to avoid unwanted
side-effects of load() which is meant to be called from other modules,
typically by parser.YamlParser().
Change-Id: I0fde43c5c27ddf78f18dc244d8dba5bd768306b7
aa5d6a538d