mapcar list truncates argument list!

[Faré]

Using a fairly recent SBCL from git on Linux x64 at commit 31d4aef.

 (apply 'mapcar 'list '((1 2 3) (4 5 6) (7 8 9)))

Expected result:
((1 4 7) (2 5 8) (3 6 9))

Instead I get:
((1 7 NIL) (2 8 NIL) (3 9 NIL))

Something bad happens to the argument list.

[Jan Moringen (scymtym)]

Seems to be fixed by (arg args (cdr args)) -> (arg args (cdr arg)) in line 1251 of list.lisp