clarify logic in case where no ZkState, sets last commit offset to HEAD
clarify logic in case where no ZkState, sets last commit offset to HEAD

raviperi/storm,0x726d77/storm,F30/storm,knusbaum/incubator-storm,ujfjhz/storm,kevpeek/storm,Aloomaio/incubator-storm,raviperi/storm,hmcc/storm,knusbaum/incubator-storm,0x726d77/storm,roshannaik/storm,srishtyagrawal/storm,ujfjhz/storm,sakanaou/storm,kishorvpatil/incubator-storm,erikdw/storm,sakanaou/storm,metamx/incubator-storm,raviperi/storm,hmcc/storm,cluo512/storm,kevinconaway/storm,kishorvpatil/incubator-storm,Aloomaio/incubator-storm,adityasharad/storm,kevpeek/storm,kamleshbhatt/storm,kamleshbhatt/storm,pczb/storm,cluo512/storm,erikdw/storm,ujfjhz/storm,srishtyagrawal/storm,knusbaum/incubator-storm,F30/storm,pczb/storm,metamx/incubator-storm,adityasharad/storm,kamleshbhatt/storm,hmcl/storm-apache,sakanaou/storm,ujfjhz/storm,F30/storm,srdo/storm,Aloomaio/incubator-storm,ujfjhz/storm,srdo/storm,cluo512/storm,knusbaum/incubator-storm,srdo/storm,raviperi/storm,knusbaum/incubator-storm,Crim/storm,Crim/storm,kishorvpatil/incubator-storm,kishorvpatil/incubator-storm,0x726d77/storm,kevinconaway/storm,cluo512/storm,srishtyagrawal/storm,erikdw/storm,kevinconaway/storm,kevpeek/storm,0x726d77/storm,sakanaou/storm,sakanaou/storm,raviperi/storm,hmcl/storm-apache,kamleshbhatt/storm,hmcc/storm,cluo512/storm,sakanaou/storm,hmcc/storm,kamleshbhatt/storm,kevinconaway/storm,F30/storm,Crim/storm,roshannaik/storm,roshannaik/storm,carl34/storm,pczb/storm,kishorvpatil/incubator-storm,Crim/storm,kevinconaway/storm,kishorvpatil/incubator-storm,kevpeek/storm,adityasharad/storm,hmcl/storm-apache,erikdw/storm,Aloomaio/incubator-storm,kevpeek/storm,erikdw/storm,roshannaik/storm,cluo512/storm,adityasharad/storm,kevpeek/storm,Crim/storm,roshannaik/storm,metamx/incubator-storm,knusbaum/incubator-storm,carl34/storm,srdo/storm,Aloomaio/incubator-storm,srdo/storm,Crim/storm,carl34/storm,sakanaou/storm,carl34/storm,cluo512/storm,knusbaum/incubator-storm,Aloomaio/incubator-storm,kevpeek/storm,raviperi/storm,erikdw/storm,ujfjhz/storm,Aloomaio/incubator-storm,srishtyagrawal/storm,0x726d77/storm,pczb/storm,srdo/storm,kamleshbhatt/storm,pczb/storm,srishtyagrawal/storm,srishtyagrawal/storm,hmcc/storm,kevinconaway/storm,hmcl/storm-apache,metamx/incubator-storm,srishtyagrawal/storm,kishorvpatil/incubator-storm,carl34/storm,roshannaik/storm,0x726d77/storm,carl34/storm,pczb/storm,hmcl/storm-apache,roshannaik/storm,erikdw/storm,pczb/storm,raviperi/storm,Crim/storm,F30/storm,srdo/storm,hmcc/storm,adityasharad/storm,kevinconaway/storm,adityasharad/storm,ujfjhz/storm,hmcl/storm-apache,metamx/incubator-storm,hmcc/storm,hmcl/storm-apache,carl34/storm,F30/storm,0x726d77/storm,adityasharad/storm,F30/storm,kamleshbhatt/storm