Drupal update to specific version (not dev) with git
Just to expand on this for future reference:

Releases in git are created as tags.  To see the available releases, do the initial pull from the repo, then you can see the available tags with the command:

git tag


To check out the specific release, do:

git checkout [tag-id]


You will see a message about previous head and current head.

Check that you are on the correct tag with:

git status


It should indicate that you are currently in a headless state.