hgweb: make log streams compatible with command server

Even though it would be useless to start a web server by a command server,
it should be doable in principle. Also, we can't use sys.stdout/err directly
on Python 3 because they are unicode streams.

mercurial/hgweb/server.py

@@ -281,8 +281,8 b' class MercurialHTTPServer(_mixin, httpse'
             prefix = '/' + prefix.strip('/')
         self.prefix = prefix
 
-        alog = openlog(ui.config('web', 'accesslog', '-'), sys.stdout)
-        elog = openlog(ui.config('web', 'errorlog', '-'), sys.stderr)
+        alog = openlog(ui.config('web', 'accesslog', '-'), ui.fout)
+        elog = openlog(ui.config('web', 'errorlog', '-'), ui.ferr)
         self.accesslog = alog
         self.errorlog = elog