报错内容：：The pipeline caused an error: Pipeline process 5 (iteration) caused an error: Redundant argument in sprintf at /usr/bin/pt-query-digest line 2556.
小弟初学，望指点。
pt-query-digest本身的BUG，升级到 2.2.20。
ref:http://stackoverflow.com/questions/38245395/pipeline-process-5-iteration-caused-an-error-redundant-argument-in-sprintf-at