Raw local files do not pass through the backing store detector and thus
the code did not allocate the required backing store terminator for
them. Previously the terminating element would be formatted into the XML
since the default values used for the metadata allowed that. This is a
regression since a693fdba01 which was not detected in the review.
This patch also reverts all the changes in the test files.
The terminator would not be parsed properly since the XPath selector was
looking for an populated element, and also the code did not bother
assigning the terminating virStorageSourcePtr to the backingStore
property of the parent.
Some tests would catch it if there wasn't bigger fallout from the change
to backing store termination in a693fdba01. Fix them properly now.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1509110
Express a properly terminated backing chain by putting a
virStorageSource of type VIR_STORAGE_TYPE_NONE in the chain. The newly
used helpers simplify this greatly.
The change fixes a bug as formatting an incomplete backing chain and
parsing it back would end up in expressing a terminated chain since
src->backingStoreRaw was not populated. By relying on the terminator
object this can be now processed appropriately.
