number_chars/2 unexpected value in rebis-dev

[UWN]

On this branch I get:

ulrich@gupu:/opt/gupu/rebis-dev$ git status
On branch rebis-dev-pr-2967
Your branch is up to date with 'origin/rebis-dev_opt-in-offset-tbl-concurrency'.

nothing to commit, working tree clean
ulrich@gupu:/opt/gupu/rebis-dev$ target/release/scryer-prolog -v
v0.9.4-468-g60695e8c
ulrich@gupu:/opt/gupu/rebis-dev$ target/release/scryer-prolog -f
?- number_chars(N,"a").
   N = a, unexpected.
   syntax_error(...). % this works in master