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.
http://mercurial.selenic.com/bts/issue1502
Initialize repository
$ hg init foo
$ touch foo/a && hg -R foo commit -A -m "added a"
adding a
$ hg clone foo foo1
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "bar" > foo1/a && hg -R foo1 commit -m "edit a in foo1"
$ echo "hi" > foo/a && hg -R foo commit -m "edited a foo"
$ hg -R foo1 pull -u
pulling from $TESTTMP/foo (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
not updating: crosses branches (merge branches or update --check to force update)
$ hg -R foo1 book branchy
$ hg -R foo1 book
* branchy 1:e3e522925eff
Pull. Bookmark should not jump to new head.
$ echo "there" >> foo/a && hg -R foo commit -m "edited a again"
$ hg -R foo1 pull
pulling from $TESTTMP/foo (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
$ hg -R foo1 book
* branchy 1:e3e522925eff