Miscomputed limit
(%i1) :lisp *features* (GCL-WORKING-PROCLAIMS CL MK-DEFSYSTEM COMPILER NUMLIB PCL-STRUCTURES PORTABLE-COMMONLOOPS PCL TURBO-CLOSURE-ENV-SIZE TURBO-CLOSURE SDEBUG DEFPACKAGE ANSI-CL COMMON-LISP GNU-LD XGCL UNEXEC NATIVE-RELOC EDITLINE TRUNCATE_USE_C CLX-LITTLE-ENDIAN BSD GNU LINUX X86_64 SGC IEEE-FLOATING-POINT UNIX GMP GCL AKCL COMMON KCL) (%i1)
Correction: It's still (si::readline-off), not (si::editline-off).
--disable-readline does not disable GCL's editline support