Github state is updated until the cocoon backend receives the first pub/sub task status. This can cause a race conditions when there is a long list of pending tasks.

The following is an example of the current workflow:

• The webhook get a new PR event and it triggers the LUCI tasks(https://github.com/flutter/cocoon/blob/master/app_dart/lib/src/request_handlers/github_webhook.dart#L178).
• Later on when the task gets scheduled it sends a pubsub that is processed by luci_status(https://github.com/flutter/cocoon/blob/master/app_dart/lib/src/request_handlers/luci_status.dart).

When there are bots available the status is updated almost immediately, but if all the resources are busy the status update can happen after 45mins in the worst case scenario.
in order to avoid this the webhook need to update the datastore to pending just after triggering the tasks.