[PATCH 1 of 3] util: add a getfstype method

[Jun Wu]

# HG changeset patch
# User Jun Wu <quark at fb.com>
# Date 1490295525 25200
#      Thu Mar 23 11:58:45 2017 -0700
# Node ID 235f1212559d03f115e21992b5725a7dc7787632
# Parent  2c02bb7fd7fc1212029dc903527e35a9efb7dbe1
# Available At https://bitbucket.org/quark-zju/hg-draft
#              hg pull https://bitbucket.org/quark-zju/hg-draft -r 235f1212559d
util: add a getfstype method

The util version is a thin wrapper of the osutil version, which is not
always available.

diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -1368,4 +1368,11 @@ def fspath(name, root):
     return ''.join(result)
 
+def getfstype(dirpath):
+    '''Get the filesystem type name from a directory (best-effort)
+
+    Returns None if we are unsure, or errors like ENOENT, EPERM happen.
+    '''
+    return getattr(osutil, 'getfstype', lambda x: None)(dirpath)
+
 def checknlink(testfile):
     '''check whether hardlink count reporting works properly'''