1.2.4

• If input/multi_file is specified, concat_dim is now optional: If concat_dim is given, the multi-file combination method is "nested", otherwise "by_coords", which was the former default. (See xarray.open_mfdatset().)

• Fixed ignored output/append_dim setting. (#54)

• Fixed broken unit level test test_multi_file_with_defaults (#52)

• Update some unit tests for compatibility with current xarray and Zarr versions.