tests/test-issue619

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

mkdir t
cd t
hg init
echo a > a
hg ci -Ama -d '1000000000 0'
echo b > b
hg branch b
hg ci -Amb -d '1000000000 0'
hg co -C 0

echo fast-forward
hg merge b
hg ci -Ammerge -d '1000000000 0'

echo bogus fast-forward should fail
hg merge b

echo done