rcutil: don't check if defaultrc/ is a directory -- we know it is

`mercurial/defaultrc/` is a directory both in the Mercurial repo and
once installed on a target platform. The directory was created in
c4ce077588d0 (config: introduce "built-in" default configuration
settings in default.d, 2014-09-04). That commit has some more
information, but it still doesn't seem to say that `defaultrc/` (then
called `default.d/`) could be a file. Perhaps the check was there to
allow you to run the same code on an older install/repo?

Differential Revision: https://phab.mercurial-scm.org/D7624

mercurial/rcutil.py

@@ -1,109 +1,106 b''
 # rcutil.py - utilities about config paths, special config sections etc.
 #
 #  Copyright Mercurial Contributors
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import os
 
 from . import (
     encoding,
     pycompat,
     util,
 )
 
 from .utils import resourceutil
 
 if pycompat.iswindows:
     from . import scmwindows as scmplatform
 else:
     from . import scmposix as scmplatform
 
 fallbackpager = scmplatform.fallbackpager
 systemrcpath = scmplatform.systemrcpath
 userrcpath = scmplatform.userrcpath
 
 
 def _expandrcpath(path):
     '''path could be a file or a directory. return a list of file paths'''
     p = util.expandpath(path)
     if os.path.isdir(p):
         join = os.path.join
         return sorted(
             join(p, f) for f, k in util.listdir(p) if f.endswith(b'.rc')
         )
     return [p]
 
 
 def envrcitems(env=None):
     '''Return [(section, name, value, source)] config items.
 
     The config items are extracted from environment variables specified by env,
     used to override systemrc, but not userrc.
 
     If env is not provided, encoding.environ will be used.
     '''
     if env is None:
         env = encoding.environ
     checklist = [
         (b'EDITOR', b'ui', b'editor'),
         (b'VISUAL', b'ui', b'editor'),
         (b'PAGER', b'pager', b'pager'),
     ]
     result = []
     for envname, section, configname in checklist:
         if envname not in env:
             continue
         result.append((section, configname, env[envname], b'$%s' % envname))
     return result
 
 
 def defaultrcpath():
     '''return rc paths in defaultrc'''
-    path = []
     defaultpath = os.path.join(resourceutil.datapath, b'defaultrc')
-    if os.path.isdir(defaultpath):
-        path = _expandrcpath(defaultpath)
-    return path
+    return _expandrcpath(defaultpath)
 
 
 def rccomponents():
     '''return an ordered [(type, obj)] about where to load configs.
 
     respect $HGRCPATH. if $HGRCPATH is empty, only .hg/hgrc of current repo is
     used. if $HGRCPATH is not set, the platform default will be used.
 
     if a directory is provided, *.rc files under it will be used.
 
     type could be either 'path' or 'items', if type is 'path', obj is a string,
     and is the config file path. if type is 'items', obj is a list of (section,
     name, value, source) that should fill the config directly.
     '''
     envrc = (b'items', envrcitems())
 
     if b'HGRCPATH' in encoding.environ:
         # assume HGRCPATH is all about user configs so environments can be
         # overridden.
         _rccomponents = [envrc]
         for p in encoding.environ[b'HGRCPATH'].split(pycompat.ospathsep):
             if not p:
                 continue
             _rccomponents.extend((b'path', p) for p in _expandrcpath(p))
     else:
         normpaths = lambda paths: [
             (b'path', os.path.normpath(p)) for p in paths
         ]
         _rccomponents = normpaths(defaultrcpath() + systemrcpath())
         _rccomponents.append(envrc)
         _rccomponents.extend(normpaths(userrcpath()))
     return _rccomponents
 
 
 def defaultpagerenv():
     '''return a dict of default environment variables and their values,
     intended to be set before starting a pager.
     '''
     return {b'LESS': b'FRX', b'LV': b'-c'}