Work-around build problem. The check for a valid file-name did not previously exclude the path separator. Fixing this breaks the compilation of the basis library because the pre-built compilers use OS.Path.joinDirFile and, erroneously, call it with a path rather than a single file arc.  For the moment we allow them as a work-around.
Work-around build problem.
The check for a valid file-name did not previously exclude the path separator.
Fixing this breaks the compilation of the basis library because the pre-built
compilers use OS.Path.joinDirFile and, erroneously, call it with a path rather
than a single file arc.  For the moment we allow them as a work-around.

polyml/polyml,polyml/polyml,dcjm/polyml,mn200/polyml,polyml/polyml,mn200/polyml,mn200/polyml,polyml/polyml,dcjm/polyml,dcjm/polyml,mn200/polyml,dcjm/polyml