"PublishServerDescriptor hidserv" publishes a public relay descriptor

I ran a Tor instance with the following lines in its torrc:

ORPort 51412
BridgeRelay 1
ExitPolicy reject *:*
PublishServerDescriptor hidserv

(There were other non-comment lines in the torrc, including lines specifying hidden services, but those are not relevant.)

I expected this Tor instance to publish hidden service descriptors and not publish any router descriptor (whether bridge or public relay). Instead, it published a router descriptor as a public relay.

The hidserv parameter to the PublishServerDescriptor torrc option is obsolete, it is ignored by the code that publishes hidden service descriptors (even v0 descriptors), and the configuration-parsing code should explicitly ignore it (and print a warning).