Where does Drupal get the date of dev version of a module?

When I view /admin/reports/updates/list and look at the entry for modules the end with "-dev" it is followed by a date.

For example, "Webform 6.x-3.x-dev (2011-Feb-28)"

Where does this report get the date at the end from?

As an aside, I ask because I updated a module fro开发者_如何学编程m my local git working copy and uploaded all the changed files to my production server, after testing of course :)

However, it didn't change this date. I would like to know more about where that date comes from.

In the module's .info file, there should be a section that looks like this:

; Information added by drupal.org packaging script on 2010-09-04
version = "6.x-2.0-beta3"
core = "6.x"
project = "apachesolr"
datestamp = "1283604104"

the date comes from the datestamp, and the Drupal.org packaging script adds that when it creates the download. Dev downloads are packaged every 12 hours, so a new one will be created when a developer commits to the development branch.

If you are checking modules directly out of git on drupal.org, you'll need to run the git deploy module to get the proper version and date information.