(Very) unexpected syntax extension

```
ulrich@gupu:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -v
v0.10.0-17-ge4d96925
ulrich@gupu:/opt/gupu/scryer-prolog$ target/release/scryer-prolog -f
?- use_module(library(dcgs)).
   true.
?- {!*[|]*}=T.
   T = {*}, unexpected. % ???????
   syntax_error(...).
