shelve: choose where .orig file locations are kept

This patch uses cmdutil.origpath to let the user set the location of the orig
files.

hgext/shelve.py

@@ -507,7 +507,7 b' def mergefiles(ui, repo, wctx, shelvectx'
         # revert will overwrite unknown files, so move them out of the way
         for file in repo.status(unknown=True).unknown:
             if file in files:
-                util.rename(file, file + ".orig")
+                util.rename(file, cmdutil.origpath(ui, repo, file))
         ui.pushbuffer(True)
         cmdutil.revert(ui, repo, shelvectx, repo.dirstate.parents(),
                        *pathtofiles(repo, files),

tests/test-shelve.t

@@ -1135,7 +1135,7 b' Test visibility of in-memory changes ins'
 
   $ cd ..
 
-test Abort unshelve always gets user out of the unshelved state
+test .orig files go where the user wants them to
 ---------------------------------------------------------------
   $ hg init salvage
   $ cd salvage
@@ -1144,10 +1144,16 b' test Abort unshelve always gets user out'
   $ echo '' > root
   $ hg shelve -q
   $ echo 'contADDent' > root
-  $ hg unshelve -q
+  $ hg unshelve -q --config 'ui.origbackuppath=.hg/origbackups'
   warning: conflicts while merging root! (edit, then use 'hg resolve --mark')
   unresolved conflicts (see 'hg resolve', then 'hg unshelve --continue')
   [1]
+  $ ls .hg/origbackups
+  root.orig
+  $ rm -rf .hg/origbackups
+
+test Abort unshelve always gets user out of the unshelved state
+---------------------------------------------------------------
 Wreak havoc on the unshelve process
   $ rm .hg/unshelverebasestate
   $ hg unshelve --abort