tests/test-double-merge

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

echo line 1 > foo
hg ci -qAm 'add foo' -d "1000000 0"

# copy foo to bar and change both files
hg cp foo bar
echo line 2-1 >> foo
echo line 2-2 >> bar
hg ci -m 'cp foo bar; change both' -d "1000000 0"

# in another branch, change foo in a way that doesn't conflict with
# the other changes
hg up -qC 0
echo line 0 > foo
hg cat foo >> foo
hg ci -m 'change foo' -d "1000000 0"

# we get conflicts that shouldn't be there
hg merge --debug

echo "-- foo --"
cat foo

echo "-- bar --"
cat bar