the timeseries ts_status.log needs to be more flexible

[bertinia]

If the history slice streams specified in the env_timeseries.xml file are turned on and off between subsequent submissions of the timeseries batch script, then the ts_status.log file will cause errors because a previous stream may not be present.

For example, for the first run submission of the timeseries script only the pop.h stream is set to "True" in the env_timeseries.xml file, a ts_status.log file is created. With a second submission of the timeseries script where the clm2.h0 stream is set to "True" then the ts_status.log file is read in cesm_tseries_generator.py and the clm2.h0 component is not present and so the process fails.