fix for update loop

Signed-off-by: camillo-positano <camillo.positano@hotmail.it>

app/src/main/java/com/owncloud/android/datamodel/ThumbnailsCacheManager.java

@@ -1426,6 +1426,7 @@ public final class ThumbnailsCacheManager {
             // resized dimensions and set update thumbnail needed to false to prevent rendering loop
             if (thumbnail != null) {
                 file.setImageDimension(new ImageDimension(thumbnail.getWidth(), thumbnail.getHeight()));
+                file.setUpdateThumbnailNeeded(false);
                 storageManager.saveFile(file);
             }
         }