[Graph]: fix a bug in increasing the merge gap size.
[Graph]: fix a bug in increasing the merge gap size.

zheng-da/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashGraph,icoming/FlashGraph,zheng-da/FlashX,zheng-da/FlashX,icoming/FlashX,zheng-da/FlashX,zheng-da/FlashX,flashxio/FlashX,flashxio/FlashX,flashxio/FlashX,icoming/FlashX,icoming/FlashX,icoming/FlashGraph,flashxio/FlashX,icoming/FlashGraph,icoming/FlashX,icoming/FlashGraph,flashxio/FlashX