$resources cache conflict when same nested resource is repeated

[seancorfield]

Discovered by Greg Thrush:

    variables.framework.routes = [
      { "$RESOURCES" = { resources = "users", nested = "logs" }},
      { "$RESOURCES" = { resources = "sites", nested = "logs" }},
    ];

The problem is the cache key in getResourceRoutes() -- it doesn't take anything but resourcesToRoute into account.