[PATCH 1 of 3] error: add a new exception named WdirRevNotSupportedError

[Pulkit Goyal]

# HG changeset patch
# User Pulkit Goyal <7895pulkit at gmail.com>
# Date 1495201237 -19800
#      Fri May 19 19:10:37 2017 +0530
# Node ID 10bab5388a7f11060a76c10d28d60578b428fdb0
# Parent  67026d65a4fcea1a121930b9736469687c095e3e
error: add a new exception named WdirRevNotSupportedError

This error will be raised when we try to use the 'wdir()' revset and support
for it has not added yet.

diff --git a/mercurial/error.py b/mercurial/error.py
--- a/mercurial/error.py
+++ b/mercurial/error.py
@@ -177,6 +177,9 @@
 class ProgrammingError(RuntimeError):
     """Raised if a mercurial (core or extension) developer made a mistake"""
 
+class WdirRevNotSupportedError(IndexError):
+    """An exception which is raised when 'wdir()' is not supported"""
+
 # bundle2 related errors
 class BundleValueError(ValueError):
     """error raised when bundle2 cannot be processed"""