[PATCH 1 of 2] windows: open registry keys using unicode names

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1536886493 14400
#      Thu Sep 13 20:54:53 2018 -0400
# Node ID 82be987da1489e3ff7411540b473690e6039fd67
# Parent  98e5168116983dfcac1a3b99169b9c0504778ac4
windows: open registry keys using unicode names

Python3 complained it must be str.  While here, use a context manager to close
the key- it wouldn't wrap at 80 characters the old way, and would have had to
move anyway.

diff --git a/mercurial/windows.py b/mercurial/windows.py
--- a/mercurial/windows.py
+++ b/mercurial/windows.py
@@ -554,9 +554,10 @@ def lookupreg(key, valname=None, scope=N
         scope = (scope,)
     for s in scope:
         try:
-            val = winreg.QueryValueEx(winreg.OpenKey(s, key), valname)[0]
-            # never let a Unicode string escape into the wild
-            return encoding.unitolocal(val)
+            with winreg.OpenKey(s, encoding.unifromlocal(key)) as hkey:
+                val = winreg.QueryValueEx(hkey, valname)[0]
+                # never let a Unicode string escape into the wild
+                return encoding.unitolocal(val)
         except EnvironmentError:
             pass