If battery status is unknown don't send BATTERY_LOW intent

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>

services/java/com/android/server/BatteryService.java

@@ -271,6 +271,7 @@ class BatteryService extends Binder {
              * - is not plugged and battery level crosses the WARNING boundary (becomes < 15).
              */
             final boolean sendBatteryLow = !plugged
+                && mBatteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN
                 && mBatteryLevel < BATTERY_LEVEL_WARNING
                 && (oldPlugged || mLastBatteryLevel >= BATTERY_LEVEL_WARNING);