The module was using ap_getword with a space for a stop character, preventing it from parsing arguments to the require directive separated by tabs. The following patch seems to fix the problem by calling ap_getword_white, which uses isspace().
Index: apache-1.3/src/modules/standard/mod_auth.c =================================================================== RCS file: /cvs/apache-1.3/src/modules/standard/mod_auth.c,v retrieving revision 1.39 diff -r1.39 mod_auth.c 267c267 < w = ap_getword(r->pool, &t, ' '); --- > w = ap_getword_white(r->pool, &t);
