Paolo Amoroso writes:

The current CVS sources of Scigraph generate a package lock error during compilation or load with recent versions of CMUCL, I think the 19a prerelease and release series. It is caused by a conflict with the symbol `cl:variable'. The problem can be fixed by changing in file Apps/Scigraph/scigraph/package.lisp the form:

(eval-when (compile load eval) (defpackage GRAPH #-allegro (:nicknames gr) ; "GR" names something already. #+allegro (:shadow variable) ; shouldn't be inherited but is #+MCL (:shadow copy) (:use dwim-lisp tool statistics)))

to this, which removes the conditionalization of `variable' shadowing for allegro:

(eval-when (compile load eval) (defpackage GRAPH #-allegro (:nicknames gr) ; "GR" names something already. (:shadow variable) ; shouldn't be inherited but is #+MCL (:shadow copy) (:use dwim-lisp tool statistics)))

Patch applied. Thanks.