Bug 139511 [CommonNavigator] getParent() fails in certain cases
In the implementation of getParents(), clients can sometimes fail to return the correct parent with the override cases taken into account. The attached patch fixes these issues, but should be reviewed by the Team Team to ensure that it does not cause any regressions for their cases.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptorManager.java
* add the descriptor as an overriding extension for its
					 * suppressed extension
					 */
					overriddenDescriptor.getOverriddingExtensions().add(
							descriptor);
					descriptor.setOverriddenDescriptor(overriddenDescriptor);
					/*
					 * the always policy implies this is also a top-level
					 * extension
					 */
					if (descriptor.getOverridePolicy() == OverridePolicy.InvokeAlwaysRegardlessOfSuppressedExt) {
						firstClassDescriptors.put(descriptor.getId(),
								descriptor);
					}
				} else {
					NavigatorPlugin.logError(0,
							"Invalid suppressedExtensionId (\"" 
									+ descriptor.getSuppressedExtensionId()
									+ "\" specified from " 
									+ descriptor.getContribution()
											.getPluginId()
									+ ". No extension with matching id found.", 
							null);
				}
			}
		}
	}
 
	private ImageRegistry getImageRegistry() {
		if (imageRegistry == null) {