sbcl: method-function doesn't like closer-mop's extra key args

[ecpeterson]

Here's closer-mop setting up a call to a method-function:

https://github.com/pcostanza/closer-mop/blob/master/closer-mop-shared.lisp#L246

and here's sbcl assembling a method-function:

https://github.com/sbcl/sbcl/blob/549ce81b4bb44ffa706b3bbec32f54f68e51df2f/src/pcl/vector.lisp#L833

Running this as-is gives a argument count mismatch: 6 supplied, 2 expected. Erasing closer-mop's key args seems to give the right behavior.

[pcostanza]

Please provide a test case that triggers a problem. Your description is too vague for me to do anything about this. Thanks.