Handle diamond merges correctly.

If we have branches top, left, right, and bottom, and left == right,
then creating a change on top should create two changes with the same
sha on left and right, and only a single change on bottom.

top -> left -> bottom, and top -> right -> bottom simultaneously.

Change-Id: I8813cefb7cb7052b435dbef4e1af422c516e13a0
4 files changed
tree: 2815f37ea295cacdb9dd091b7c65b38b75f76421
  1. src/
  2. .gitignore
  3. BUILD
  4. external_plugin_deps.bzl
  5. LICENSE
  6. LICENSE-re2j