Hilariously, at no point in this patch had we started this service process

hyperthunk · hyperthunk · commit 02494f2de06b · 2018-11-13T15:05:12.000Z
This does seem to indicate that either the tests are not really validating anything useful, or the issue was a non-issue to begin with. This patch nevertheless contains useful improvements to our tracing of registration events, so I think it's still valid.
diff --git a/src/Control/Distributed/Process/Node.hs b/src/Control/Distributed/Process/Node.hs
@@ -376,6 +376,7 @@ startServiceProcesses node = do
     -- loops during tracing if the user reregisters the "logger" with a custom
     -- process which uses 'send' or other primitives which are traced.
     register "trace.logger" logger
+    void $ registryMonitorAgent
  where
    loop = do
      receiveWait
