[PATCH 1 of 3] histedit: add inprogress method to state class

[Christian Delahousse]

# HG changeset patch
# User Christian Delahousse <cdelahousse at fb.com>
# Date 1444088057 25200
#      Mon Oct 05 16:34:17 2015 -0700
# Node ID a4ca3731ba2ccb54d2a549876fa74f55a84216bb
# Parent  875e5d89dc86a616ac43c12519ded0d1d75e13f5
histedit: add inprogress method to state class

If a histedit is progress, the 'histedit-state' file should exist. The patch
implements a convenience function to do check if a histedit is in progress.

This method will be use in next patch in the series.

diff --git a/hgext/histedit.py b/hgext/histedit.py
--- a/hgext/histedit.py
+++ b/hgext/histedit.py
@@ -312,6 +312,9 @@
     def clear(self):
         self.repo.vfs.unlink('histedit-state')
 
+    def inprogress(self):
+        return self.repo.vfs.exists('histedit-state')
+
 class histeditaction(object):
     def __init__(self, state, node):
         self.state = state