# HG changeset patch
# User Cédric Krier <ced@b2ck.com>
# Date 1596382835 -7200
#      Sun Aug 02 17:40:35 2020 +0200
# Branch stable
# Node ID 49f8ba4febec5100ee84b49afef63e19879fa75d
# Parent  3d414dce2d40bd8d20efdd0ac03659ed1aba2f7e
keepalive: Do not append _rbuf if _raw_readinto exists (issue6356)

The readline method append to the chunks the content of the _rbuf then there
is a loop that call _raw_read which on Python3 call readinto. But the readinto
version in mercurial append again the _rbuf content. So this creates the
duplicate content. This does not happen in Python2 because _raw_read does not
call readinto.

Differential Revision: https://phab.mercurial-scm.org/D8859

diff --git a/mercurial/keepalive.py b/mercurial/keepalive.py
--- a/mercurial/keepalive.py
+++ b/mercurial/keepalive.py
@@ -542,7 +542,11 @@
             return line
 
         # No newline in local buffer. Read until we find one.
-        chunks = [self._rbuf]
+        # readinto read via readinto will already return _rbuf
+        if self._raw_readinto is None:
+            chunks = [self._rbuf]
+        else:
+            chunks = []
         i = -1
         readsize = self._rbufsize
         while True: