Use the Repair button, pick HPM and it will update to the latest.
If you have an older, older version of HPM, you may have to repair twice, once to get to the latest in the original, which is there to shift to the new. The second Repair will bring you all the way over to the v1.8.7 version.
A handful of people have run into this:
The list of package owners, called the Master Repo, no longer is updated for the old versions. v1.8.3 is where we shifted to the Community repo and by updating you'll probably find some interesting Packages. 
