Fixes an MR compilation error, HADOOP-6904 added a new implementation of getProtocolSignature but TestTaskCommit doesn't override it.
Integrated in Hadoop-Mapreduce-trunk #643 (See https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk/643/)
Integrated in Hadoop-Mapreduce-trunk-Commit #595 (See https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk-Commit/595/)
Thanks Nigel. I've committed this.
+1. please commit.
Patch attached. Fixes the compilation error and TestTaskCommit passes.