tests/test-issue612.t

upgrade: use the repository 'ui' as the base for the new repository

The `repo.baseui` contains all the configuration but the one specific to the
repository (so it can be used when dealing with local peer and sub-
repository). However, we need the repository config to be taken into account
when doing the upgrade. Otherwise, the upgrade related config that exists in
the repository config won't be taken into account when performing the update.
A buggy and surprising behavior.

We had to work around protection set around `repo.ui.copy` since we are an
uncommon case.

https://bz.mercurial-scm.org/612

  $ hg init
  $ mkdir src
  $ echo a > src/a.c
  $ hg ci -Ama
  adding src/a.c

  $ hg mv src source
  moving src/a.c to source/a.c (glob)

  $ hg ci -Ammove

  $ hg co -C 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo new > src/a.c
  $ echo compiled > src/a.o
  $ hg ci -mupdate
  created new head

  $ hg status
  ? src/a.o

  $ hg merge
  merging src/a.c and source/a.c to source/a.c
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status
  M source/a.c
  R src/a.c
  ? src/a.o