Fix for NuGet Gallery #417

gistfile1.cs

var allPackageVersions = packagesQuery.ToList();
var packageVersions = allPackageVersions; ;            
if (String.IsNullOrEmpty(version) && !allowPrerelease) 
{
    // If there's a specific version given, don't bother filtering by prerelease. You could be asking for a prerelease package.
    packageVersions = packageVersions.Where(p => !p.IsPrerelease).ToList();
}