[PATCH 2 of 2 STABLE] setup: filter out devel-warn messages from system hg

[Kevin Bullock]

# HG changeset patch
# User Kevin Bullock <kbullock+mercurial at ringworld.org>
# Date 1508814839 18000
#      Mon Oct 23 22:13:59 2017 -0500
# Branch stable
# Node ID adc50614340e952d8e98f5948d35b7bf632c2232
# Parent  f13a8d056d6ebf490e65096391fdcd5916197f48
setup: filter out devel-warn messages from system hg

If we're going to use the user's installed and configured hg command
(which we do since 8b20338b989e), we should prevent devel-warn messages
from interfering with locating it.

diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -218,7 +218,8 @@ def filterhgerr(err):
     err = [e for e in err.splitlines()
            if (not e.startswith(b'not trusting file')
                and not e.startswith(b'warning: Not importing')
-               and not e.startswith(b'obsolete feature not enabled'))]
+               and not e.startswith(b'obsolete feature not enabled')
+               and not e.startswith(b'devel-warn:'))]
     return b'\n'.join(b'  ' + e for e in err)
 
 def findhg():