Set bitbucket user as option in installer

Our organization uses some software to deploy users to servers (and doesn't allow other users than those). Sadly, it's not possible to use more than 8 letters for a user.

So, atlbitbucket isn't allowed (confluence btw, isn't, too) and we use user git for bitbucket.

Anytime, when I upgrade Bitbucket, I have to do the upgrade and chown /opt/atlassian/bitbucket, /home/git/application, /home/git/repositories just because your installer gives them all to atlbitbucket.

this is a little effort but also, a high risk. (best neccessary work is no neccessary work..) So why isn't it possible to install with a --bitbucket-user option?