NuGet's Restore Package insists on specific package versions
===

I've a project with the following packages.config:

    <?xml version="1.0" encoding="utf-8"?>
    <packages>
      <package id="Framework.Infrastructure.Core" version="1.4.0.6" />
      <package id="Framework.Infrastructure.Extensions" version="1.4.0.6" />
    </packages>

Where the Framework.* packages are sitting in our local repository.

I've enabled Package Restore and added our internal repo to the sources. However, when I try restoring the packages from packages.config (which essentially does `nuget install packages.config -sources....`), I get the following errors:

    error : Unable to find version '1.4.0.6' of package 'Framework.Infrastructure.Extensions'
    error : Unable to find version '1.4.0.6' of package 'Framework.Infrastructure.Core'.

The repository no longer contains the **1.4.0.6** version of the package (which was relevant a couple of months ago), but rather the new version of it (e.g., **1.5.1.6**).

Why doesn't NuGet find the new versions of the packages? Is there some syntax I can specify in packages.config to ensure that the latest versions will be downloaded?

In short, is there anything short of writing a custom script to update the packages that I can do?

Thank you.