My original thought so I built it on Linux and retested. I managed to get the problem in the first session but haven't been able to repeat after that.
ariel:7.7 $ ./bin/pike Pike v7.7 release 45 running Hilfe v3.5 (Incremental Pike Frontend)
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[^-^]%s", string res) && res;
(1) Result: "hello"
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
(2) Result: 0
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
(3) Result: 0
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
Error in sscanf format string. HilfeInput:1: HilfeInput()->___HilfeWrapper()
sscanf("^^^^^^^^hello", "%*[^]%s", string res) && res;
(4) Result: 0