Queue blocked with Backoff strategy

[jdG-]

Describe the bug
I have a queue with a backoff strategy. If I add a new job to the queue and the previous one is still retrying, the newly added one is stuck and will be started once the first finished.

To Reproduce
13:00 create queue with backoff strategy (retry every 30minutes)
13:01 add new job #1 in the queue (retries: 1)
13:01 job #1 fails
13:10 add new job #2 in the queue (retries: 1)
13:31 job #1 succeeded
13:31 job #2 succeeded

Expected behavior
13:00 create queue with backoff strategy (retry every 30minutes)
13:01 add new job #1 in the queue (retries: 1)
13:01 job #1 fails
13:10 add new job #2 in the queue (retries: 1)
13:10 job #2 succeeded
13:31 job #1 succeeded

Environment (please complete the following information):

• @vendure/core version: 1.0.0-beta.8
• Nodejs version: 12.20
• Database (mysql/postgres etc): postgres