As of somewhere between 5.1.x and 5.2.x, we eliminated proxy.config.proxy_name from records.config.in. It used to be set to the build machine name, but now we default to the one in RecordsConfig.cc (which is <proxy_name>).
I'd like to suggest we do one of two things (please voice your opinion):
1) Restore the proxy.config.proxy_name into records.config.in, with the old setting (@buildmachine@).
2) Use the hostname from the Machine object. This is basically gethostname().
I think I prefer #2, but I'm also open for other suggestions.