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
monitor.worked(50);
						monitor
								.subTask(DataTransferMessages.WizardProjectsImportPage_ProcessingMessage);
						while (filesIterator.hasNext()) {
							selectedProjects[index++] = (ProjectRecord) filesIterator
									.next();
						}
					} else if (!dirSelected
							&& ArchiveFileManipulations.isZipFile(path)) {
						ZipFile sourceFile = getSpecifiedZipSourceFile(path);
						if (sourceFile == null) {
							return;
						}
						structureProvider = new ZipLeveledStructureProvider(
								sourceFile);
						Object child = structureProvider.getRoot();
						if (!collectProjectFilesFromProvider(files, child, 0,
								monitor)) {
							return;
						}
						Iterator filesIterator = files.iterator();
						selectedProjects = new ProjectRecord[files.size()];
						int index = 0;
						monitor.worked(50);
						monitor
								.subTask(DataTransferMessages.WizardProjectsImportPage_ProcessingMessage);
						while (filesIterator.hasNext()) {
							selectedProjects[index++] = (ProjectRecord) filesIterator
									.next();
						}