The HKPS proxy on 443/tcp at sks-keyservers.net hasn't been operable
for many months (consistently returning a 502 Bad Gateway error).
Switch to a direct HKP URL on 11371/tcp at pool.sks-keyservers.net
instead, which returns the same content (unfortunately not over an
encrypted connection). The next best alternatives would be to use a
lookup on keyserver.ubuntu.com which misses a lot of the
cross-signing key info, or keys.openpgp.net which only provides a
link to download key material with no additional information and no
signatures.
Change-Id: If7f6e84b9de625f13013189ea04c0a311ac10609
c453d884df