exchange: move code related to exchange into a 'evolve.exchange' submodule
The evolve extension is HUGE, we split exchange code appart before doing more work on it.
#!/bin/sh
# This file holds logic that is used in many tests.
# It can be called in a test like this:
# $ . "$TESTDIR/testlib"
# Enable obsolete markers and enable extensions
cat >> $HGRCPATH << EOF
[experimental]
evolution=createmarkers,exchange
[extensions]
rebase=
EOF
echo "topic=$(echo $(dirname $TESTDIR))/hgext3rd/topic" >> $HGRCPATH