Fix up lock handling in hgweb_config_manager

    def __init__(self):

        self.hgweb_config_dir = None

        self.in_memory_config = None

        self.lock = threading.Lock()

    def add_entry(self, lhs, rhs):

        """Add an entry in the hgweb.config file for a new repository."""

        lock = threading.Lock()

        lock.acquire(True)

        self.lock.acquire(True)

        try:

            # Since we're changing the config, make sure the latest is loaded into memory.

            self.read_config(force_read=True)

        except Exception as e:

            log.debug("Exception in HgWebConfigManager.add_entry(): %s", unicodify(e))

        finally:

            lock.release()

            self.lock.release()

    def change_entry(self, old_lhs, new_lhs, new_rhs):

        """Change an entry in the hgweb.config file for a repository - this only happens when the owner changes the name of the repository."""

        lock = threading.Lock()

        lock.acquire(True)

        self.lock.acquire(True)

        try:

            self.make_backup()

            # Remove the old entry.

        except Exception as e:

            log.debug("Exception in HgWebConfigManager.change_entry(): %s", unicodify(e))

        finally:

            lock.release()

            self.lock.release()

    def get_entry(self, lhs):

        """Return an entry in the hgweb.config file for a repository"""