lrowe/lxml — comment on commit 573816cf2488f0d0fd223c63c34f1b7536cc20db
File: src/lxml/cssselect.py line 85
By scoder:

The problem here is that this might break code that uses both ```contains()``` and namespaces, because the regex namespace is only being declared when no namespaces are passed in. The original global declaration isn't ideal either - I think the best way to do this would be to register the regex namespace in the namespaces dict if it is not declared yet, and to use an uncommon prefix to avoid naming conflicts (not perfect, though...).