How to determine in which version an Android bug was fixed? How does one determine when a specific Android bug was fixed?

Specifically, I'm interested in learning in which Android version bug 58779 was fixed.

Someone marked it obsolete, which either means it has been fixed or someone erroneously marked it that way.
You already link the open source issue tracker. So I will assume you want a more in depth inquiry. Then just Go to Androids Gerrit code review and you can go directly here. Or you can go through Googles Git repository here then code review  in the upper right. Once there you can search for changes here is a tutorial. You can also review the code that will give you detailed information and here is a tutorial for that.