On Windows, 'run script.sh' makes Dune try to run CreateProcess() on the script
itself. Adding 'bash' prevents an error. Since the shebang of the script also
mentions bash, this should keep the previous behavior on Unix.

Splits on ACSL predicates do not try to split and reduce states in which the
predicate is already satisfied or refuted.

A split has failed if the reduced state is equal to the entry state _and_
the predicate evaluates to Unknown.
If the predicate evaluates to True/False in the entry state, then the state
cannot be reduced: the reduced state is then equal to the entry state), but
this is not a failure: the split holds.