Thanks for the correction Georg.

In msg104113 (on #8350), I quoted http://docs.python.org/dev/reference/expressions#calls :

“An implementation may provide built-in functions whose positional parameters do not have names, even if they are ‘named’ for the purpose of documentation, and which therefore cannot be supplied by keyword.”

Previous consensus seemed to be that this warning was enough, but recent bugs such as this one show that it does trip up users, so there is further discussion about how best to document this CPython limitation (hence the dependency I’m adding).