Response is dropping stationxml decimation element

I have a test StationXML file that is part of the IRIS validation test suite.
It contains a response with this stage in it:

<Stage number="1">

This stage does not specify a PolesZeros/Coefficients/etc element; it
is designed to fail IRIS validation rule 423.
Obspy reads this stage into a generic ResponseStage but it drops the decimation
information (e.g., stage.decimation_input_sample_rate is None), making it look like any other stage containing only a stage.stage_gain.

Is this a bug ?

I’ll attach the xmlfile to this post.

F1_423.xml (30.0 KB)

Nevermind - looking through the code I can see that it expects a stage
to be one of the 5 types:
type_elems = [poles_zeros_elem, coefficients_elem, response_list_elem,
fir_elem, polynomial_elem]

and for these it will pass the decimation info in **kwargs to instantiate the object,
or else it simply returns the base ResponseStage without any additional info (like decimation).

So I guess I’ll have to trap this particular case using lxml directly.