Fix the bug of batch delete when the delete count is larger than 1000.
Fix the bug of batch delete when the delete count is larger than 1000.

liangchao07115/qshell,liangchao07115/qshell,qiniu-lab/qshell,qiniu-lab/qshell,qiniu/qshell,jemygraw/qshell,jemygraw/qshell