Comment 3 for bug 548612

Theoretical view: libraries messing with signal handlers is in bad style as different signal handling strategies don't compose at all so fix the library. More practically, are you sure that INSTALL-HANDLER (should be called via ENABLE-INTERRUPT) does not call sigaction again? As far as I can tell by reading install_handler that's only happens when a "low level" interrupt handler was installed.

Be them low level or not these are often critical enough that removing the SBCL handler even for a short while can compromise the image (e.g. SIGSEGV) or some functionality (e.g. SIGALRM, ). So which signal are we talking about here?