diff -r 26a31c88e1a5 -r 716d575df275 mercurial/revlog.py
--- a/mercurial/revlog.py	Sun Aug 04 22:14:26 2019 +0200
+++ b/mercurial/revlog.py	Wed Jun 12 14:22:49 2019 +0100
@@ -2461,7 +2461,8 @@
                 # the revlog chunk is a delta.
                 cachedelta = None
                 rawtext = None
-                if destrevlog._lazydelta:
+                if (deltareuse != self.DELTAREUSEFULLADD
+                        and destrevlog._lazydelta):
                     dp = self.deltaparent(rev)
                     if dp != nullrev:
                         cachedelta = (dp, bytes(self._chunk(rev)))