diff -r 5517d62c1bcc -r dbc5ead9f40f mercurial/revlog.py
--- a/mercurial/revlog.py	Sat Aug 18 23:17:06 2018 -0700
+++ b/mercurial/revlog.py	Thu Aug 16 04:50:32 2018 +0200
@@ -2661,7 +2661,7 @@
         self._writeentry(transaction, ifh, dfh, entry, data, link, offset)
 
         if alwayscache and rawtext is None:
-            rawtext = deltacomputer._buildtext(revinfo, fh)
+            rawtext = deltacomputer.buildtext(revinfo, fh)
 
         if type(rawtext) == bytes: # only accept immutable objects
             self._cache = (node, curr, rawtext)