attribute names with trailing underscores are not references

[amueller]

This is more of a question.
In scikit-learn we name out attributes with trailing underscores like

Attributes
==========
bla_ : ndarray
   Nothing useful

I remember that at some point, we needed to enclose the attribute in backticks to not get an error about undefined references. Then at some point, we didn't need to do that any more. I just upgraded us to numpydoc master, and now I have to add the backticks in a gain.
Were there any intentional changes in that? It's also possible that we hacked this somewhere ourselves, but I can't find the relevant change in the code :(

[amueller]

I think this is because attribute descriptions used to be generated by SphinxDocString._str_param_list but now they are generated by SphinxDocStr._str_member_list. I'm not entirely sure what the difference is.