If RS passes 127.0.0.1, then thats what its bound too and no (remote) client will be able to connect. Its broke.
The fixup in master would let this (broke) server successfully register. The master would call remoteIP on the connected socket to get the RSs' address and it would then know the RS as this. This would happen only on startup, in reportForDuty, not subsequently during heartbeating; we only do the lookup of remoteip on reportForDuty.
Heartbeating, the RS was supposed to be volunteering the HServerInfo that the Master had passed it back as response to the reportForDuty.
Since 0.90.0, servers can register at heartbeat time. This is because masters can join an already running cluster. The RSs do not rerun the reportForDuty step. They just start heartbeating the new Master.
We could I suppose add lookup on the sockets remoteip to heartbeating too with reverse lookup.
I'm thinking its better to just strip all this crap out.