See: https://github.com/GoogleCloudPlatform/gcloud-python/pull/1145/files#r40020506 `gcloud._helpers._RFC3339_MICROS` is used to parse datetime strings in: - `gcloud.dns.changes` (after #1145 lands) - `gcloud.pubsub.message` - `gcloud.storage.bucket` - `gcloud.storage.blob` (twice)