Allow update.bash without git fetch/pull

[strayer]

I'm using Ansible to install zram-config and set a specific git tag I'd like to check out (e.g. v1.5.0). I configured Ansible to run update.bash when it changes the checked out git repo (e.g. when I change the Ansible config from v1.4.0 to v1.5.0).

Problem is that update.bash always fetches and checks out the main branch. I'd like to be able to just let it update the installed files after checking out a branch/tag myself.

Thanks for your work!