Added network bug workaround

app/src/main/java/eu/faircode/email/ConnectionHelper.java

@@ -187,7 +187,13 @@ public class ConnectionHelper {
         Network active = cm.getActiveNetwork();
         if (active == null) {
             Log.i("isMetered: no active network");
-            return null;
+            // Workaround bug in some Android versions
+            NetworkInfo ani = cm.getActiveNetworkInfo();
+            if (ani == null || !ani.isConnected()) {
+                Log.i("isMetered: no active network=" + (ani == null ? null : ani.isConnected()));
+                return null;
+            }
+            return cm.isActiveNetworkMetered();
         }
 
         // onLost [... state: DISCONNECTED/DISCONNECTED ... available: true]