--- a/mercurial/unionrepo.py	Wed Aug 07 20:51:52 2019 +0200
+++ b/mercurial/unionrepo.py	Wed Aug 07 21:17:48 2019 +0200
@@ -116,6 +116,9 @@
             # already cached
         return text
 
+    def rawdata(self, nodeorrev, _df=None):
+        return self.revision(nodeorrev, _df=_df, raw=True)
+
     def baserevision(self, nodeorrev):
         # Revlog subclasses may override 'revision' method to modify format of
         # content retrieved from revlog. To use unionrevlog with such class one