How to extract source headers from gdal WMS driver?

I am using gdal.Warp and Mapzen Terrain Tiles in Python to generate arbitrary digital elevation models. I see in the Terrain Tiles Documentation that the Mapzen Terrain Tiles service will return a HTTP response containing source information for the data.

How can I access these source headers?

Here is an example of my call to gdal.Warp:

gdal.Warp(
    'my_output_tiff.tif',
    'wms_descriptor_file.xml',
    options=gdal.WarpOptions(
        format='GTiff',
        outputBounds=(west_x, south_y, east_x, north_y),
        outputBoundsSRS='EPSG:4326',
    )
)

Where ‘my_output_tiff.tif’ is just the outputted file, ‘wms_descriptor_file.xml’ is a WMS XML descriptor file formatted according to the WMS documentation, and the output bounds are the bounding box for the area of interest.