message: go: Support un-built-yet dependencies.
diff: @@ -323,6 +323,14 @@ class Toolkit:
  """
  assert isinstance(node, Source)
  import json
  + if not node.path().is_file():
  + try:
  + # FIXME: is building a node during dependencies ok ?
  + # See drake.cxx._mkdeps for more detail.
  + node.build()
  + except drake.NoBuilder:
  + # If a node is found but cannot be built, let drake fail by itself.
  + pass
  res = json.loads(self.run(['list', '-json', str(node.path())]))
  deps = res['Deps']
  deps.extend(res.get('TestImports', []))
  