tests/test-1102.t

bundlerepo: enforce reading from core repo only

We do not want anything computed with the bundle overlay to be written back in
the repo. Such write will likely contains invalid data.

The short terms goal of this change is to drop use of `_cacheabletip` in bundle
repo.

  $ rm -rf a
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ hg tag t1 # 1
  $ hg tag --remove t1 # 2

  $ hg co 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tag -f -r0 t1
  $ hg tags
  tip                                3:a49829c4fc11
  t1                                 0:f7b1eb17ad24

  $ cd ..