Apparently a NASA mission last year called DART (Demonstration for Autonomous Rendezvous Technology) was supposed to test robotic docking of two spaceships. Huh, I hadn't ever heard of it. Which is seemingly all to the good as far as NASA is concerned: "the full 70-page document contains details protected by the International Traffic in Arms Regulations, space agency spokesman Michael Braukus said." [CNN/AP] About all they've released is that it was a fuel problem but NOT a fuel leak. Not that informative. Hm.
Meanwhile, this does not bode well for robotic repair or even deorbiting of the HST.