diff -r 1fc39367eafd -r 98995b689e03 mercurial/httppeer.py
--- a/mercurial/httppeer.py	Sat Sep 08 23:57:07 2018 +0800
+++ b/mercurial/httppeer.py	Sat Sep 08 21:58:51 2018 +0800
@@ -401,8 +401,8 @@
     elif version_info == (0, 2):
         # application/mercurial-0.2 always identifies the compression
         # engine in the payload header.
-        elen = struct.unpack('B', resp.read(1))[0]
-        ename = resp.read(elen)
+        elen = struct.unpack('B', util.readexactly(resp, 1))[0]
+        ename = util.readexactly(resp, elen)
         engine = util.compengines.forwiretype(ename)
 
         resp = engine.decompressorreader(resp)