diff -r f0fadc5bea21 -r a4942675de6b mercurial/revlog.py
--- a/mercurial/revlog.py	Sat May 19 18:58:35 2018 +0530
+++ b/mercurial/revlog.py	Sat May 19 18:59:21 2018 +0530
@@ -846,7 +846,7 @@
     def rawsize(self, rev):
         """return the length of the uncompressed text for a given revision"""
         l = self.index[rev][2]
-        if l >= 0:
+        if l is not None and l >= 0:
             return l
 
         t = self.revision(rev, raw=True)