columnstore-docker-cluster: cej user not being able to be renamed through environment variable

jens@ubuntu18:~/columnstore-docker-cluster$ cat .env

# S3 Variables

ASYNC_CONN=0

ANALYTICS_ONLY=1

USE_S3_STORAGE=0

S3_BUCKET=

S3_ENDPOINT=

S3_REGION=

S3_ACCESS_KEY_ID=

S3_SECRET_ACCESS_KEY=

# Host Variables

PM1=mcs1

PM2=mcs2

PM3=mcs3

MX1=mx1

# Credentials

CMAPI_KEY=

ADMIN_USER=

ADMIN_PASS=

CEJ_USER=skysql_cej

CEJ_PASS=

MAX_USER=

MAX_PASS=

REP_USER=

REP_PASS=

jens@ubuntu18:~/columnstore-docker-cluster$ docker-compose up -d

Creating network "columnstore-docker-cluster_default" with the default driver

Creating volume "columnstore-docker-cluster_data1" with default driver

Creating volume "columnstore-docker-cluster_data2" with default driver

Creating volume "columnstore-docker-cluster_data3" with default driver

Creating volume "columnstore-docker-cluster_storagemanager" with default driver

Creating mcs3 ... done

Creating mcs2 ... done

Creating mcs1 ... done

Creating mx1  ... done

jens@ubuntu18:~/columnstore-docker-cluster$ sleep 60 && docker exec -it mcs1 mariadb -e "SELECT user,host FROM mysql.user"

+-------------+-----------+

| User        | Host      |

+-------------+-----------+

| cej         | %         |

| idbrep      | %         |

| maxscale    | %         |

| mariadb.sys | localhost |

| mysql       | localhost |

| root        | localhost |

+-------------+-----------+