[PATCH 2 of 7 mergedriver] shelve: switch to mergestate.read()

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1447797370 28800
#      Tue Nov 17 13:56:10 2015 -0800
# Node ID 185e1c423b1fd2ff38dc687c5736754968a57d22
# Parent  225459dfc6cad40339467f2ba72b33f00709b6d6
shelve: switch to mergestate.read()

See previous patches for why we're doing this.

diff --git a/hgext/shelve.py b/hgext/shelve.py
--- a/hgext/shelve.py
+++ b/hgext/shelve.py
@@ -531,7 +531,7 @@ def unshelvecontinue(ui, repo, state, op
     lock = None
     try:
         checkparents(repo, state)
-        ms = merge.mergestate(repo)
+        ms = merge.mergestate.read(repo)
         if [f for f in ms if ms[f] == 'u']:
             raise error.Abort(
                 _("unresolved conflicts, can't continue"),