ShuffleMetrics.ShuffleConnections Gauge Metric Rises Infinitely

We recently noticed that the mapred.ShuffleMetrics.ShuffleConnections metric rises indefinitely (see attached graph), despite supposedly being a gauge measuring the number of currently open connections:

    @Metric("# of current shuffle connections")
        MutableGaugeInt shuffleConnections;

It seems this is because the metric is incremented once for each map file sent, but decremented once for each request. Thus a request which fetches multiple map files permanently increments shuffleConnections by (mapsFetched - 1).