I've been routinely building SBCL since its version 1.0.37 using clisp-2.48 for bootstrapping. At the moment the latest SBCL successfully built with clisp-2.48 is sbcl-1.0.40.
Using clisp-2.49 built with exactly the same libraries as clisp-2.48 breaks sbcl-1.0.40 build. I am not a lisp guy and I do not know whether SBCL uses something illegal/deprecated from CLISP, but the breakage is a fact.
I am about to upload SBCL 'make' scree output showing the problem.