pmlogrewrite: put back optimization in the absence of event records
pmlogrewrite: put back optimization in the absence of event records

Need to be a bit more careful to preserve the temporal index,
especially in the "copy and no rewrite" cases.

andyvand/cygpcpfans,wuliming/pcp,adfernandes/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,prasincs/pcp,adfernandes/pcp,aeg-aeg/pcpfans,adfernandes/pcp,aeg-aeg/pcpfans,aeg-aeg/pcpfans,tjanez/pcp,andyvand/cygpcpfans,tjanez/pcp,prasincs/pcp,andyvand/cygpcpfans,aeg-aeg/pcpfans,wuliming/pcp,wuliming/pcp,tjanez/pcp,adfernandes/pcp,tjanez/pcp,prasincs/pcp,wuliming/pcp,tjanez/pcp,tjanez/pcp,adfernandes/pcp,tjanez/pcp,prasincs/pcp,prasincs/pcp,tjanez/pcp,prasincs/pcp,prasincs/pcp,wuliming/pcp,wuliming/pcp,edwardt/pcp,edwardt/pcp,edwardt/pcp,adfernandes/pcp,prasincs/pcp,andyvand/cygpcpfans,edwardt/pcp,andyvand/cygpcpfans,andyvand/cygpcpfans,wuliming/pcp,wuliming/pcp,aeg-aeg/pcpfans,edwardt/pcp,edwardt/pcp,aeg-aeg/pcpfans,andyvand/cygpcpfans,aeg-aeg/pcpfans,edwardt/pcp,adfernandes/pcp,edwardt/pcp,adfernandes/pcp