HDFS-7867. Update action param from 'start' to 'prepare' in rolling upgrade ( Contributed by J.Andreina) Updated JIRA id.
HDFS-7867. Update action param from 'start' to 'prepare' in rolling upgrade ( Contributed by J.Andreina) Updated JIRA id.

(cherry picked from commit 355e008ffbb0a33cb7d5782fc291abd62d684aaa)

Microsoft-CISL/hadoop-prototype,satishpatil2k13/ODPI-Hadoop,satishpatil2k13/ODPI-Hadoop,zrccxyb62/hadoop,Microsoft-CISL/hadoop-prototype,MjAbuz/hadoop,intel-hadoop/hadoop,MjAbuz/hadoop,satishpatil2k13/ODPI-Hadoop,zrccxyb62/hadoop,intel-hadoop/hadoop,intel-hadoop/hadoop,satishpatil2k13/ODPI-Hadoop,Microsoft-CISL/hadoop-prototype,intel-hadoop/hadoop,MjAbuz/hadoop,zrccxyb62/hadoop,MjAbuz/hadoop,satishpatil2k13/ODPI-Hadoop,zrccxyb62/hadoop,Microsoft-CISL/hadoop-prototype,zrccxyb62/hadoop,intel-hadoop/hadoop,MjAbuz/hadoop,zrccxyb62/hadoop,zrccxyb62/hadoop,MjAbuz/hadoop,satishpatil2k13/ODPI-Hadoop,Microsoft-CISL/hadoop-prototype,MjAbuz/hadoop,intel-hadoop/hadoop,Microsoft-CISL/hadoop-prototype,satishpatil2k13/ODPI-Hadoop,intel-hadoop/hadoop,Microsoft-CISL/hadoop-prototype,Microsoft-CISL/hadoop-prototype,satishpatil2k13/ODPI-Hadoop