rcutil: split osrcpath to return default.d paths (API)

After this change, there are 3 rcpath functions:

  - defaultrcpath
  - systemrcpath
  - userrcpath

This will allow us to insert another config layer in the middle.

mercurial/rcutil.py

@@ -1,64 +1,62
 # 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,
     osutil,
     pycompat,
     util,
 )
 
 if pycompat.osname == 'nt':
     from . import scmwindows as scmplatform
 else:
     from . import scmposix as scmplatform
 
 systemrcpath = scmplatform.systemrcpath
 userrcpath = scmplatform.userrcpath
 
-def osrcpath():
-    '''return default os-specific hgrc search path'''
+def defaultrcpath():
+    '''return rc paths in default.d'''
     path = []
     defaultpath = os.path.join(util.datapath, 'default.d')
     if os.path.isdir(defaultpath):
         for f, kind in osutil.listdir(defaultpath):
             if f.endswith('.rc'):
                 path.append(os.path.join(defaultpath, f))
-    path.extend(systemrcpath())
-    path.extend(userrcpath())
-    path = [os.path.normpath(f) for f in path]
     return path
 
 _rcpath = None
 
 def rcpath():
     '''return hgrc search path. if env var HGRCPATH is set, use it.
     for each item in path, if directory, use files ending in .rc,
     else use item.
     make HGRCPATH empty to only look in .hg/hgrc of current repo.
     if no HGRCPATH, use default os-specific path.'''
     global _rcpath
     if _rcpath is None:
         if 'HGRCPATH' in encoding.environ:
             _rcpath = []
             for p in encoding.environ['HGRCPATH'].split(pycompat.ospathsep):
                 if not p:
                     continue
                 p = util.expandpath(p)
                 if os.path.isdir(p):
                     for f, kind in osutil.listdir(p):
                         if f.endswith('.rc'):
                             _rcpath.append(os.path.join(p, f))
                 else:
                     _rcpath.append(p)
         else:
-            _rcpath = osrcpath()
+            paths = defaultrcpath() + systemrcpath() + userrcpath()
+            _rcpath = pycompat.maplist(os.path.normpath, paths)
     return _rcpath