A ValueError is raised when running the object_container module with the
`metadata` param against a container with existing metadata.
When the module attempts to enumerate the existing container metadata, a
ValueError exception is raised, because the code is iterating over the
metadata keys, instead of `dict_items`.
Compare to the iteration through another dict `metadata` on the next
line:
new_metadata = dict((k, v) for k, v in metadata.items()
This change adds a call to `items()` on the dictionary.
Note that this is added outside the parentheses so that the behaviour of the
`or` statement is not affected, and that another exception isn't caused
if `container.metadata` is not a dict.
Closes-Bug: #2071934
Change-Id: Ie5e1f275839e38340a75ab18c3b9ec9bc7745d68
e0dc4776bb