Reindexing just by the (1D) timeseries or as a Series this works (in 0.10.1):
data_1.reindex(rng, method = 'ffill')
data_1.reindex(Series(rng, index=rng), method = 'ffill')
.
With date_rng
as the DataFrame I get TypeError: Cannot compare Timestamp with 0, I suspect this could be a bug, but I'm not entirely sure what the expected behaviour should be...