[PATCH 2 of 2] shelve: add dirstateguard to unshelve

[Durham Goode]

# HG changeset patch
# User Durham Goode <durham at fb.com>
# Date 1443492037 25200
#      Mon Sep 28 19:00:37 2015 -0700
# Node ID 50ce9941d7c0ce0abf4b3c9e616057a82e6c9021
# Parent  ff1ab706e6d662d1971c1a6127e60b7063abfe74
shelve: add dirstateguard to unshelve

If unshelve threw an exception at an inopportune moment, it would cause an
unknown working copy parent. Adding the dirstateguard prevents this.

I tested it by manually introducing exceptions in various locations within
unshelve.

diff --git a/hgext/shelve.py b/hgext/shelve.py
--- a/hgext/shelve.py
+++ b/hgext/shelve.py
@@ -619,6 +619,8 @@ def unshelve(ui, repo, *shelved, **opts)
         wlock = repo.wlock()
         lock = repo.lock()
 
+        dsguard = cmdutil.dirstateguard(repo, 'unshelve')
+
         tr = repo.transaction('unshelve', report=lambda x: None)
         oldtiprev = len(repo)
 
@@ -676,6 +678,7 @@ def unshelve(ui, repo, *shelved, **opts)
                 })
             except error.InterventionRequired:
                 tr.close()
+                dsguard.close()
 
                 stripnodes = [repo.changelog.node(rev)
                               for rev in xrange(oldtiprev, len(repo))]
@@ -695,6 +698,7 @@ def unshelve(ui, repo, *shelved, **opts)
                 shelvectx = tmpwctx
 
         mergefiles(ui, repo, pctx, shelvectx)
+        dsguard.close()
         shelvedstate.clear(repo)
 
         # The transaction aborting will strip all the commits for us,
@@ -708,6 +712,8 @@ def unshelve(ui, repo, *shelved, **opts)
         ui.quiet = oldquiet
         if tr:
             tr.release()
+        if dsguard:
+            dsguard.release()
         lockmod.release(lock, wlock)
 
 @command('shelve',