Fix income/pull with bundle and -R (issue 820).
Uses ui.setconfig() to tell bundlerepo where the main repo is. This is
needed for when the --repository option is used.
Adds tests to test-bundle and a new test script
test-mq-pull-from-bundle, which plays out the situation that initially
made me detect this bug
(hg -R .hg/patches pull ../bundle.hg).
#!/bin/sh
hg init repo
cd repo
touch foo
hg ci -Am 'add foo'
hg up -C null
# this should be stored as a delta against rev 0
echo foo bar baz > foo
hg ci -Am 'add foo again'
hg debugindex .hg/store/data/foo.i