saks028 is broken on Windows

Strangely, the saks028 test is broken on Windows:

--- saks/should_compile/saks028.run/saks028.stderr.normalised	2019-11-07 13:40:00.117411000 +0000
+++ saks/should_compile/saks028.run/saks028.comp.stderr.normalised	2019-11-07 13:40:00.118386600 +0000
@@ -1 +0,0 @@
-(* -> *) -> Constraint

This is deeply mysterious given the size of the test and the fact that it apparently exits with a 0 exit code.