Fix media URL extension for m4a uploads

server/media/fs/filesys.go

@@ -9,7 +9,6 @@ import (
 	"errors"
 	"hash/fnv"
 	"io"
-	"mime"
 	"net/http"
 	"net/url"
 	"os"
@@ -141,10 +140,7 @@ func (fh *fshandler) Upload(fdef *types.FileDef, file io.Reader) (string, int64,
 	}
 
 	fname := fdef.Id
-	ext, _ := mime.ExtensionsByType(fdef.MimeType)
-	if len(ext) > 0 {
-		fname += ext[0]
-	}
+	fname += media.ExtensionByMimeType(fdef.MimeType)
 
 	fdef.Location = location
 	// Use file path to create ETag. File paths are unique so will be the ETag.