Upgrade 7.2.6 -> 7.3.0 fails

Expect
I should be able to upgrade from 7.2.6 to 7.3.0 tags

Observed
Upgrades fail with permission denied when performing stat on {{ splunk_home}}/etc/auth/splunk.secret

Repro Steps

1. docker-compose up -d
2. docker-compose logs splunkenterprise --follow
3. Wait for splunkweb to be available
4. change image tag in compose to ":7.3.0" or ":edge"
5. add env var SPLUNK_UPGRADE="true"
6. docker-compose up -d
7. docker-compose logs splunkenterprise

Docker Compose File

# docker run splunk/enterprise:7.0.3
# Options on how to review the EULA and accept it: 
# 1. docker run -it splunk/enterprisetrial:7.0.3
# 2. Add the following environment variable: SPLUNK_START_ARGS=--accept-license
# e.g., docker run -e "SPLUNK_START_ARGS=--accept-license" splunk/enterprisetrial 

# Support for Docker Compose v3, https://docs.docker.com/compose/overview/
version: '3'
volumes:
  opt-splunk-etc:
  opt-splunk-var:
services:
  splunkenterprise:
    #build: .
    hostname: splunkenterprise
    image: splunk/splunk:7.2.6
    image: splunk/splunk:7.3.0
    #image: splunk/splunk:edge
    environment:
      SPLUNK_START_ARGS: --accept-license --answer-yes
      DEBUG: "true"
      ANSIBLE_EXTRA_FLAGS: "-vvvv"
      SPLUNK_PASSWORD: 'icanhazpasswd'
      # SPLUNK_UPGRADE: "true"
      SPLUNK_ENABLE_LISTEN: 9997
      SPLUNK_ADD: tcp 1514
    volumes:
      - opt-splunk-etc:/opt/splunk/etc
      - opt-splunk-var:/opt/splunk/var
    ports:
      - "8000:8000"
      - "9997:9997"
      - "8088:8088"
      - "1514:1514"