Lab 5 multispectral image issues

[keves1]

In lab 5 the Landsat image (https://github.com/opengeos/datasets/releases/download/raster/cog.tif) only has 4 bands, but band 5 (NIR) is needed to calculate NDWI in exercise 4.

src.meta:

{'driver': 'GTiff',
 'dtype': 'float64',
 'nodata': None,
 'width': 343,
 'height': 206,
 'count': 4,
 'crs': CRS.from_wkt('GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AXIS["Latitude",NORTH],AXIS["Longitude",EAST],AUTHORITY["EPSG","4326"]]'),
 'transform': Affine(8.983152841195215e-05, 0.0, 6.860074498707138,
        0.0, -8.983152841195215e-05, 53.41634207654228)}

When I run src = rasterio.open('https://github.com/opengeos/datasets/releases/download/raster/cog.tif') to open the image, I get this warning:

WARNING:rasterio._env:CPLE_AppDefined in cog.tif: TIFFReadDirectory:Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples.

I'm not sure if that is related to the image only having 4 bands or not.