While building the dependency graph, also follow aliases.

Aliases might lead us to a different package that we don't know
about yet.

bant/explore/dependency-graph.cc

@@ -162,7 +162,14 @@ DependencyGraph BuildDependencyGraph(Session &session,
           // The list to insert all the dependencies our current target has.
           std::vector<BazelTarget> &depends_on =
             graph.depends_on.insert({*target_or, {}}).first->second;
-          for (const auto dep : query::ExtractStringList(result.deps_list)) {
+
+          // Follow dependencies and alias references.
+          auto to_follow = query::ExtractStringList(result.deps_list);
+          if (!result.actual.empty()) {
+            to_follow.push_back(result.actual);
+          }
+
+          for (const auto dep : to_follow) {
             auto dependency_or = BazelTarget::ParseFrom(dep, current_package);
             if (!dependency_or.has_value()) continue;