Only reset pin.watchLastCount when it is valid.

Clover/app/src/main/java/org/floens/chan/core/model/Pin.java

@@ -54,7 +54,7 @@ public class Pin {
     public int watchLastCount = -1;
 
     @DatabaseField
-    public int watchNewCount = 0;
+    public int watchNewCount = -1;
 
     @DatabaseField
     public int quoteLastCount = 0;
@@ -69,7 +69,7 @@ public class Pin {
     }
 
     public int getNewPostsCount() {
-        if (watchLastCount < 0) {
+        if (watchLastCount < 0 || watchNewCount < 0) {
             return 0;
         } else {
             return Math.max(0, watchNewCount - watchLastCount);

Clover/app/src/main/java/org/floens/chan/core/watch/PinWatcher.java

@@ -58,7 +58,10 @@ public class PinWatcher implements Loader.LoaderListener {
     }
 
     public void onViewed() {
-        pin.watchLastCount = pin.watchNewCount;
+        if (pin.watchNewCount >= 0) {
+            pin.watchLastCount = pin.watchNewCount;
+        }
+
         pin.quoteLastCount = pin.quoteNewCount;
         wereNewQuotes = false;
     }