Update site from core dev to stable Using advice from Drush: Update core from stable to dev I ran drush up drupal-7.x in order to switch from 7.7 to 7.x-dev. 

However I'm now in the position whereby I want to move the project back to 7.8, however I don't seem to be able to figure out how to do this. I've tried:

drush up drupal-7.8


Which produces:

 Name         Installed version  Proposed version  Status
 Drupal core  7.x-dev            7.x-dev           Specified version available


So it appears to understand I'm asking for a new version, but following this through just updates the site to the latest 7.x-dev.
You could hack the includes/bootstrap.inc file
The very first line of code will be something like:

define('VERSION', '7.11-dev');


Set it to 7.7, and drush should accept that 7.8 is a never release.
I know that hacking core is strongly discouraged, but since the upgrade itself will remove the hack, I think it's more than ok.