How can I grab the latest "stable" repo version from the Github API?

Github's tag method returns a list of all tags pushed to your repo with the latest tag listed at the top. Here's an example call: https://api.github.com/repos/ff0000/rosy/tags which produces the following json object.

[{
    name: "rbp-folder-rename",
    zipball_url: "https://api.github.com/repos/ff0000/rosy/zipball/rbp-folder-rename",
    tarball_url: "https://api.github.com/repos/ff0000/rosy/tarball/rbp-folder-rename",
    commit: {
        sha: "09ebda2678d932a005fc86ab78f6c04eebdcd50d",
        url: "https://api.github.com/repos/ff0000/rosy/commits/09ebda2678d932a005fc86ab78f6c04eebdcd50d"
    }
},
{
    name: "2.0.10",
    zipball_url: "https://api.github.com/repos/ff0000/rosy/zipball/2.0.10",
    tarball_url: "https://api.github.com/repos/ff0000/rosy/tarball/2.0.10",
    commit: {
        sha: "fe284c7d461107d9d08d2d4dcb676759f9485fc1",
        url: "https://api.github.com/repos/ff0000/rosy/commits/fe284c7d461107d9d08d2d4dcb676759f9485fc1"
    }
},

// ....

{
    name: "2.1.5",
    zipball_url: "https://api.github.com/repos/ff0000/rosy/zipball/2.1.5",
    tarball_url: "https://api.github.com/repos/ff0000/rosy/tarball/2.1.5",
    commit: {
        sha: "db92baa49657b3c3d27b1475c415c19525cb2118",
        url: "https://api.github.com/repos/ff0000/rosy/commits/db92baa49657b3c3d27b1475c415c19525cb2118"
    }
}]

Questions

This list appears to have the latest tag at the top, followed by a history of previous tags listed in reverse chronological order. Why? That seems odd that the first result is ordered differently then the rest, maybe I'm reading this wrong?
Is there any way to programmatically retrieve the latest version applied to the master branch only? I'd like to programmatically retrieve the latest stable version of a repo.

Any help / insight would be appreciated.

Solution

You could simply replace the tag by the branch name:

https://api.github.com/repos/ff0000/rosy/zipball/master

See the more general form of that query (for a given branch) in "Is there anyway to programmatically fetch a zipball of private github repo?".

But that presume that the latest stable version of a repo is in master (it could be the latest 'development', which might not be very stable past the fact that it compile and passes basic unit test): each project can have its own convention.

For what it's worth, https://api.github.com/repos/ff0000/rosy/branches would list the branches for that same repo.