vfs: split "expand" into "realpath"/"expandpath" to apply each separately

Before this patch, vfs constructor applies both "util.expandpath()"
and "os.path.realpath()" on "base" path, if "expand" is True.

This patch splits it into "realpath" and "expandpath", to apply each
functions separately: this splitting can allow to use vfs also where
one of each is not needed.

mercurial/localrepo.py

@@ -153,7 +153,7 b' class localrepository(object):'
         return self.requirements[:]
 
     def __init__(self, baseui, path=None, create=False):
-        self.wvfs = scmutil.vfs(path, expand=True)
+        self.wvfs = scmutil.vfs(path, expandpath=True, realpath=True)
         self.wopener = self.wvfs
         self.root = self.wvfs.base
         self.path = self.wvfs.join(".hg")

mercurial/scmutil.py

@@ -263,9 +263,11 b' class vfs(abstractvfs):'
     This class is used to hide the details of COW semantics and
     remote file access from higher level code.
     '''
-    def __init__(self, base, audit=True, expand=False):
-        if expand:
-            base = os.path.realpath(util.expandpath(base))
+    def __init__(self, base, audit=True, expandpath=False, realpath=False):
+        if expandpath:
+            base = util.expandpath(base)
+        if realpath:
+            base = os.path.realpath(base)
         self.base = base
         self._setmustaudit(audit)
         self.createmode = None