Revert "don't send bulk_read_entry_response messages containing no data" (r4099)
Revert "don't send bulk_read_entry_response messages containing no data" (r4099)

-> we need this for e.g. range reads to know which ranges have been covered or not
scalaris-team/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,jvf/scalaris,caijieming-baidu/scalaris,caijieming-baidu/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris,jvf/scalaris,caijieming-baidu/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,scalaris-team/scalaris,jvf/scalaris,jvf/scalaris,scalaris-team/scalaris,caijieming-baidu/scalaris