NuGet group repository does not respect latest version filters

When searching for components across members of a group repository, a component ID at 2 different versions (one in each member repository) both report that they are the latest version in the generated feed, which is logically impossible.
Recreation:

• publish SONATYPE.TEST.1.0.nupkg to a hosted repo
• publish SONATYPE.TEST.1.1.nupkg to another hosted repo
• search for SONATYPE.TEST on a group repo containing both of the above host repos
• observe that both entries claim to be for the latest version of the component

Test for this condition is presently commented out in NugetGroupIT(search for this ticket), and should be re-enabled to confirm this when fixed.

Acceptance Criteria:

XML feed should only contain one latest version of a given package

Note:

Browse functionality works as is and hasn't been touched