avoid generating arbitrary MetaData with illegal fields

Types/MetaData.hs

@@ -264,7 +264,9 @@ parseMetaData p = (,)
 instance Arbitrary MetaData where
 	arbitrary = do
 		size <- arbitrarySizedBoundedIntegral `suchThat` (< 500)
-		MetaData . M.fromList <$> vector size
+		MetaData . M.filterWithKey legal . M.fromList <$> vector size
+	  where
+		legal k _v = legalField $ fromMetaField k
 
 instance Arbitrary MetaValue where
 	arbitrary = MetaValue <$> arbitrary <*> arbitrary

doc/bugs/git_annex_test_under_windows_8.1.mdwn

@@ -62,3 +62,6 @@ e s tDse.t
 
 # End of transcript or log.
 """]]
+
+> A sort of windows-specific bug in the test suite. I've fixed it. [[done]]
+> --[[Joey]]