Much of the time, take this field collection migration issue for example, when I find an issue with a drupal module, there has already been an issue filed, and in some cases the issue has a status of Closed (fixed). In the sidebar there is a version mentioned. It seems likely that that version is the one you set when you file the issue, specifying which branch of the code you saw the issue in.
When the issue has been Closed (fixed), does that mean that if you grab the specified version, that the code will include the patch? Is there any way of knowing when a fix has reached the stable branch?