Star Wars” was lying crunched up in a plastic bag in a London home.Now fully restored, the iconic gown is going up for public auction for the first time and is expected to fetch at least $2 million.The medieval-style dress worn by Carrie Fisher in 1977’s “Star Wars: A New Hope” is the only Princess Leia outfit from that film which has ever been discovered.“When I was first told about the dress, I simply couldn’t believe it,” props collector Stephen Lane told The Post. “I’ve been collecting for 30 years and I think it’s one of the most exciting finds of my career.”It had been kept by a member of the British crew as a memento, while many of the other costumes from the film were thrown away.