warning while purging logs with QJM enabled

HDFS-2946 changed the way that edit log purging is calculated, such that it calls selectInputStreams() with an arbitrary transaction ID calculated relative to the current one. The JournalNodes will reject such a request if that transaction ID falls in the middle of a segment (which it usually will). This means that selectInputStreams gets an exception, and the QJM journal manager is not included in this calculation. Additionally, a warning will be logged.

Purging itself still happens, because the detailed information on remote logs is not necessary to calculate a retention interval, but the feature from HDFS-2946 may not work as intended.