Load(): crashes when loading as first observation a file-per-member or -per-ensemble dataset and a 2-dimensional variable

Chloé reported this bug to me.

The failing Load() call was: meantemp=Load("prlr", c("b0cm"), obs = c("GPCP"), sdates=c("19900501"), nleadtime = 4, nmember = 10, leadtimemin = 1, leadtimemax = 2, storefreq = "monthly", sampleperiod = 1, method = "conservative", output="lonlat", ncores = 1)

[1] "* Reading & processing data... /cfu/data/noaa/gpcp_v2.2/monthly_mean/prlr/prlr_199005.nc" Error in SetRows.bm(x, i, value) : Illegal row index usage in extraction.