Entity Framework Core 1.0 DbContext not scoped to http reques

I understood by watching this video with Rowan Miller https://chael9.msdn.com/Series/Whats-New-with-ASPNET-5/06 (at minute 22) that the way of configuring Entity Framework Core (previously known as EF7) into an ASP.NET Core 1.0 app (previously known as ASP.NET 5) in Startup.cs is as follows:

    public void ConfigureServices(IServiceCollection services)
    {
        //Entity Framework 7 scoped per request??
        services.AddEntityFramework()
            .AddSqlServer()
            .AddDbContext<MyDbContext>(options =>
            {
                options
                  .UseSqlServer(Configuration["Data:DefaultCoection:CoectionString"]);
            });

        //MVC 6
        services.AddMvc();
    }

and that this DbContext will be scoped to an http request so that whenever in the code throughout the http pipeline (including middleware or MVC) a DbContext is used, we know for sure that the instance injected by the DI container will be the same.

But the problem is that it does not seem to work that way. Within the lifetime of MVC it is true that the DbContext instance injected is the same, but as described here: Entity Framework Core 1.0 unit of work with ASP.NET 5 with middleware I am trying to plug into the pipeline the following middleware to achieve some kind of centralised Commit/Rollback after a controller finalises execution:

public class UnitOfWorkMiddleware
{
    private readonly RequestDelegate _next;
    private readonly MyDbContext _dbContext;
    private readonly ILogger _logger;

    public UnitOfWorkMiddleware(RequestDelegate next, MyDbContext dbContext, ILoggerFactory loggerFactory)
    {
        _next = next;
        _dbContext = dbContext;
        _logger = loggerFactory.CreateLogger<UnitOfWorkMiddleware>();
    }

    public async Task Invoke(HttpContext httpContext)
    {
        await _next.Invoke(httpContext);
        _logger.LogInformation("Saving changes for unit of work if everything went good");
        await _dbContext.SaveChangesAsync();
    }
}

The DbContext instance in my Middleware is not the same as the instance being injected during the MVC lifetime.

Is this expected? Shouldn't a DbContext be scoped to an http request? Is possible to achieve what I was trying to achieve?