[racket] querying PLaneT repository

What's a good way to query what versions of a PLaneT package are 
available in the repository?

Options I see so far:

* Search version space using multiple "download-package" calls, which 
unfortunately downloads the entire package satisfying a query (and puts 
actual retrieved version number in nonstandard HTTP headers).

* Search version space using multiple HTTP requests (either HTTP method 
"HEAD", if that works, or prematurely dropped "GET"), using URLs from 
"pkg->download-url".

* Scraping the HTML of the Web site.  Nope.

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http://www.neilvandyke.org/