Being human, it looks like I know so little event about the tools I use every days.
I found a bug in rails, discovered it was already patched, and it dosent seems to be in the versions I currently require (3.2.3).
Here it is :
https://github.com/rails/rails/pull/5168
How would I know if a commit on master would have been packaged into a gem?
I don’t think there’s any one way to tell. You can take a look at the tags for the project, and that will tell you when new versions of rails are released. Each tag is for a specific commit. If that commit happened after the patch was merged, then the patch is most likely in that version of rails.
You could also view the source of the latest gem file and see if the patch is in there: