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
echo % should fail
hg add .hg/00changelog.i
mkdir a
echo a > a/a
hg ci -Ama
ln -s a b
echo b > a/b
echo % should fail
hg add b/b
echo % should succeed
hg add b
echo % should still fail - maybe
hg add b/b
exit 0