pull: call the `b2x-transactionclose` hook when closing the transaction
We need a wider set of hooks to process all the changes that happened during the
pull transaction. We reuse the experimental `b2x-transactionclose` hook set
from server's unbundle for consistency. This hook is experimental and will not
remains as-is forever, but this will open the door for experimentation in 3.2.
Testing that hghave does not crash when checking features
$ "$TESTDIR/hghave" --test-features 2>/dev/null