diff -r 41ef02ba329b -r 8cdb671dbd0b mercurial/sshserver.py
--- a/mercurial/sshserver.py	Mon Jan 08 19:41:47 2018 +0530
+++ b/mercurial/sshserver.py	Mon Jan 15 15:20:02 2018 -0800
@@ -76,13 +76,7 @@
 
     def sendstream(self, source):
         write = self.fout.write
-
-        if source.reader:
-            gen = iter(lambda: source.reader.read(4096), '')
-        else:
-            gen = source.gen
-
-        for chunk in gen:
+        for chunk in source.gen:
             write(chunk)
         self.fout.flush()