Sorting is not stable enough

[schemacs]

Request6ProgressKtTest.testProgress failed with this:

Wrong intermediate result after 3200: expected:<[User(login=user-2, contributions=50), User(login=user-1, contributions=50)]> but was:<[User(login=user-1, contributions=50), User(login=user-2, contributions=50)]>
Expected :[User(login=user-2, contributions=50), User(login=user-1, contributions=50)]
Actual   :[User(login=user-1, contributions=50), User(login=user-2, contributions=50)]

intro-coroutines/src/tasks/Aggregation.kt

Line 20 in c51a403

.sortedByDescending { it.contributions }

(in the solution branch) should be updated to

        .sortedWith(compareByDescending<User> { it.contributions }
            .thenByDescending { it.login })

This is my solution for Request6Progress.kt:

suspend fun loadContributorsProgress(
    service: GitHubService,
    req: RequestData,
    updateResults: suspend (List<User>, completed: Boolean) -> Unit
) {
    val repos = service
        .getOrgRepos(req.org)
        .also { logRepos(req, it) }
        .body() ?: listOf()

    var allUsers = emptyList<User>()
    repos.forEachIndexed { index, repo ->
        val users = service
            .getRepoContributors(req.org, repo.name)
            .also { logUsers(repo, it) }
            .bodyList()
        allUsers += users
        // allUsers = (allUsers + users).aggregate() // uncomment this line to make the test happy
        updateResults(allUsers.aggregate(), index == repos.lastIndex)
    }
}