Bug 162655 [Undo] [IDE] - Undoing a delete should check for existence of resources to be restored
N20061027. - I deleted two projects (along with their content). I read the warning that undo delete cannot restore the content and said "OK." - Then I checked out those same projects from HEAD. - Then I selected "Undo Delete Resources." This overwrote my code with empty projects. I think that "Undo Delete Resources" should become invalid if the resources exist again, because you'll end up replacing content without keeping a backup.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/DeleteResourcesOperation.java
* 
	 * @see org.eclipse.ui.ide.undo.AbstractWorkspaceOperation#computeExecutionStatus(org.eclipse.core.runtime.IProgressMonitor)
	 */
	public IStatus computeExecutionStatus(IProgressMonitor monitor) {
		IStatus status = super.computeExecutionStatus(monitor);
		if (status.isOK()) {
			status = computeDeleteStatus();
		}
		if (status.isOK()) {
			
			
			if (deleteContent && resourcesIncludesProjects()) {
				status = getWarningStatus(
						UndoMessages.DeleteResourcesOperation_DeletingProjectContentWarning,
						0);
			}
		}
		return status;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * Map undo status to resource creation status.
	 * 
	 * @see org.eclipse.ui.ide.undo.AbstractWorkspaceOperation#computeUndoableStatus(org.eclipse.core.runtime.IProgressMonitor)
	 */
	public IStatus computeUndoableStatus(IProgressMonitor monitor) {
		IStatus status = super.computeUndoableStatus(monitor);
		if (status.isOK()) {
			status = computeCreateStatus();