aof: fix assignment for aof_fsync_offset

Signed-off-by: NYuan Zhou <yuan.zhou@intel.com>

src/aof.c

@@ -1761,7 +1761,7 @@ void backgroundRewriteDoneHandler(int exitcode, int bysignal) {
             server.aof_selected_db = -1; /* Make sure SELECT is re-issued */
             aofUpdateCurrentSize();
             server.aof_rewrite_base_size = server.aof_current_size;
-            server.aof_current_size = server.aof_current_size;
+            server.aof_fsync_offset = server.aof_current_size;
 
             /* Clear regular AOF buffer since its contents was just written to
              * the new AOF from the background rewrite buffer. */