Bug 317954 Version deltas file so that incompatible changes will be ignored
The deltas file needs to be versioned so that incompatible changes will be discarded allowing the workbench to be constructed as if there were no deltas in existence.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/XMLModelReconciler.java
if (objectReference == null) {
								NodeList list = (NodeList) item;
								Element refElement = getFirstElement(list);
								if (refElement != null) {
									ModelDelta delta = createDelayedDelta(object, attributeFeature,
											refElement);
									deltas.add(delta);
								}
							} else {
								IDelta delta = new EMFModelDeltaSet(object, attributeFeature,
										objectReference);
								compositeDelta.add(delta);
							}
						} else if (isChainedReference(attributeName)) {
							List<Object> objectReferences = new ArrayList<Object>();
							NodeList objectReferenceNodes = (NodeList) item;
							for (int j = 0; j < objectReferenceNodes.getLength(); j++) {
								Node refNode = objectReferenceNodes.item(j);
								if (refNode instanceof Element) {
									Object objectReference = getReference(deltas,
											(Element) refNode, references);
									if (objectReference != null) {
										objectReferences.add(objectReference);
									}
								}
							}
							IDelta delta = new EMFModelDeltaSet(object, attributeFeature,
									objectReferences);
							compositeDelta.add(delta);
						} else if (isUnorderedChainedAttribute(attributeName)) {