Bug 330553 [Import/Export] Importing a project that exists in workspace location merges the contents
(1) Create a project in the default location (2) Export it to an archive (3) Delete it (but don't choose the option to delete from disk) (4) Make some changes in the <workspace root>/<project> directory (4) Import the archive you exported in step 2 This results in files from both the archive and directory. If the directory already has a file thats available in the archive, then it doesn't modify it. Ideally we shouldn't be allowing the import at all.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/WizardProjectsImportPage.java
* Performs clean-up if the user cancels the wizard without doing anything
	 */
	public void performCancel() {
		ArchiveFileManipulations.closeStructureProvider(structureProvider,
				getShell());
	}
	/**
	 * Create the project described in record. If it is successful return true.
	 * 
	 * @param record
	 * @return boolean <code>true</code> if successful
	 * @throws InterruptedException
	 */
	private boolean createExistingProject(final ProjectRecord record,
			IProgressMonitor monitor) throws InvocationTargetException,
			InterruptedException {
		String projectName = record.getProjectName();
		final IWorkspace workspace = ResourcesPlugin.getWorkspace();
		final IProject project = workspace.getRoot().getProject(projectName);
		createdProjects.add(project);
		if (record.description == null) {
			
			record.description = workspace.newProjectDescription(projectName);
			IPath locationPath = new Path(record.projectSystemFile
					.getAbsolutePath());
			
			if (Platform.getLocation().isPrefixOf(locationPath)) {
				record.description.setLocation(null);
			} else {
				record.description.setLocation(locationPath);