systemed/iD — pull request #70 by jfirebaugh (2012-11-10 01:04:27+00:00)
Title: Preserve Graph immutability

The connection calls back with a Graph, rather than updating the one
passed in the constructor in-place.

History takes care of merging the new Graph into each version. (If we used
prototype-based sharing, we could instead update a single special-case
mutable root entity map.)