fossil bisect <no args>
Segmentation fault (core dumped)

strlen(NULL) is a bad idea, at least on OpenBSD and Solaris:-)

    - mho

Index: src/bisect.c
===================================================================
--- src/bisect.c
+++ src/bisect.c
@@ -88,10 +88,13 @@
 */
 void bisect_cmd(void){
   int n;
   const char *zCmd;
   db_must_be_within_tree();
+  if (g.argc < 3) {
+    usage("bad|good|next|reset|vlist ...");
+  };
   zCmd = g.argv[2];
   n = strlen(zCmd);
   if( n==0 ) zCmd = "-";
   if( memcmp(zCmd, "bad", n)==0 ){
     int ridBad;