tests: stabilize `test-sparse.t` on Windows

One of the reserved characters for path values is '*', so it can't be used.
Fortunately, missing this seems to not get in the way of any other tests, and it
is removed shortly after with `rm -r foo*bar`, and the extant 'foo-bar' matches
the pattern.

tests/test-sparse.t

@@ -34,7 +34,9 Test that sparse pattern by default is i
   $ mk 'foo' bar
   $ mk 'foo-bar' x
   $ mk 'unanchoredfoo-bar' x
+#if no-windows
   $ mk 'foo*bar' x
+#endif
   $ mk 'dir/foo-bar' x
   $ hg status --config rhg.on-unsupported=abort
   ? dir/foo-bar/x