Fix filehandling for windows

fileutil/fileutil.go

@@ -48,7 +48,7 @@ func Rename(from, to string) error {
 // It is not atomic.
 func Replace(from, to string) error {
 	if err := os.RemoveAll(to); err != nil {
-		return nil
+		return err
 	}
 	if err := os.Rename(from, to); err != nil {
 		return err

wal.go

@@ -1272,7 +1272,6 @@ func MigrateWAL(logger log.Logger, dir string) (err error) {
 	if err != nil {
 		return errors.Wrap(err, "open old WAL")
 	}
-	defer w.Close()
 
 	rdr := w.Reader()
 
@@ -1309,6 +1308,9 @@ func MigrateWAL(logger log.Logger, dir string) (err error) {
 	if err := repl.Close(); err != nil {
 		return errors.Wrap(err, "close new WAL")
 	}
+	if err := w.Close(); err != nil {
+		return errors.Wrap(err, "close old WAL")
+	}
 	if err := fileutil.Replace(tmpdir, dir); err != nil {
 		return errors.Wrap(err, "replace old WAL")
 	}

wal/wal.go

@@ -311,16 +311,18 @@ func (w *WAL) Repair(origErr error) error {
 	if err != nil {
 		return errors.Wrap(err, "open segment")
 	}
-	defer f.Close()
 	r := NewReader(bufio.NewReader(f))
 
 	for r.Next() {
 		if err := w.Log(r.Record()); err != nil {
 			return errors.Wrap(err, "insert record")
 		}
 	}
-	// We expect an error here, so nothing to handle.
+	// We expect an error here from r.Err(), so nothing to handle.
 
+	if err := f.Close(); err != nil {
+		return errors.Wrap(err, "close corrupted file")
+	}
 	if err := os.Remove(tmpfn); err != nil {
 		return errors.Wrap(err, "delete corrupted segment")
 	}