  Any two compact, complete, one-dimensional geodesic spaces with identical
marked length spectrum have isometric $\pi_1$-hull.
  The present version contains errors, notably in Lemmas 2.2 and 2.3 (path
cancellations can be more complicated), which then propagate through the paper.
The main result is correct as stated, and a proof can be found in the joint
paper with David Constantine, arXiv:1209.3709
