test: fix race in connect_tests disconnect-deferred-failure test

test/mp/test/connect_tests.cpp

@@ -139,7 +139,13 @@ KJ_TEST("ConnectStream defers disconnect failure to the first IPC request for in
     } catch (const std::runtime_error& e) {
         std::string_view reason = e.what();
 
-        KJ_EXPECT(reason == "IPC client method called after disconnect.");
+        // There is a race between the event loop detecting the disconnect
+        // and foo->add() being called. If the onDisconnect callback fires
+        // first and nulls m_context.connection, the error is "called after
+        // disconnect"; if foo->add() submits before the callback fires,
+        // the error is "interrupted by disconnect".
+        KJ_EXPECT(reason == "IPC client method called after disconnect." ||
+                  reason == "IPC client method call interrupted by disconnect.");
     }
 }