bitbucket.properties file isn't migrated correctly when upgrading Bitbucket Server with Windows installer

Summary

bitbucket.properties file isn't migrated correctly when upgrading Bitbucket Server with Windows installer.

Environment

• Windows Server 2008 (We could also reproduce this bug on Windows 10)

Steps to Reproduce

1. Install vanilla 4.6.x (I used 4.6.2 to reproduce this bug) as a service with using the installer
2. Start the instance
3. Make the instance use External DB (I used PostgreSQL to reproduce this bug)
   • Then, bitbucket.properties file should be created in this step
4. Check if the permission of bitbucket.properties is as follows ...(1)
   
5. Stop the instance
6. Upgrade the instance to 4.7.1 with using the installer
7. Start the instance
8. Stop the instance
9. Check if the permission of bitbucket.properties is as follows ...(2)
   

Expected Results

(2) should be the same as the (1).

Actual Results

A permission to access bitbucket.properties file was taken away from Atlassian Bitbucket user and there was an unknown user on the permission list instead.

Workaround

We have to change the file permission manually.