BUG: offsets.apply doesnt preserve nanosecond
BUG: _flex_binary_moment() doesn't preserve column order or handle non-unique columns
Merge pull request #7738 from seth-p/flex_binary_moment_column_order

BUG: _flex_binary_moment() doesn't preserve column order or handle multiple columns with the same label
Merge pull request #7697 from sinhrks/offsetnano

BUG/PERF: offsets.apply doesnt preserve nanosecond
BUG: DTI.value_counts doesnt preserve tz