How to use the gitman.exceptions.UncommittedChanges function in gitman

def it_should_fail_on_dirty_repositories(config):
        expect(gitman.update(depth=1, lock=False)) == True
        shell.rm(os.path.join("deps", "gitman_1", ".project"))

        try:
            with pytest.raises(UncommittedChanges):
                gitman.lock()

            expect(config.datafile.text).does_not_contain("")

        finally:
            shell.rm(os.path.join("deps", "gitman_1"))

yn_input = str(
                            input("Do you want to overwrite? (Y/N)[Y]: ")
                        ).rstrip('\r\n')

                        if yn_input.lower() == "y" or not yn_input:
                            break

                        if yn_input.lower() == "n":
                            common.show(
                                f'Skipped update in {os.getcwd()}', color='git_changes'
                            )
                            return

            else:
                if git.changes(self.type, include_untracked=clean):
                    raise exceptions.UncommittedChanges(
                        f'Uncommitted changes in {os.getcwd()}'
                    )

        # Fetch the desired revision
        if fetch or git.is_fetch_required(self.type, self.rev):
            git.fetch(self.type, self.repo, self.name, rev=self.rev)

        # Update the working tree to the desired revision
        git.update(
            self.type, self.repo, self.name, fetch=fetch, clean=clean, rev=self.rev
        )

if allow_dirty:
                    common.show(self.DIRTY, color='git_dirty', log=False)
                    common.newline()
                    return path, url, self.DIRTY

                if skip_changes:
                    msg = ("Skipped lock due to uncommitted changes " "in {}").format(
                        os.getcwd()
                    )
                    common.show(msg, color='git_changes')
                    common.newline()
                    return path, url, self.DIRTY

                msg = "Uncommitted changes in {}".format(os.getcwd())
                raise exceptions.UncommittedChanges(msg)

            rev = git.get_hash(self.type, _show=True)
            common.show(rev, color='git_rev', log=False)
            common.newline()
            return path, url, rev

        if allow_missing:
            return os.getcwd(), '', self.UNKNOWN

        raise self._invalid_repository

def _run_command(function, args, kwargs):
    success = False
    exit_message = None
    try:
        log.debug("Running %s command...", getattr(function, '__name__', 'a'))
        success = function(*args, **kwargs)
    except KeyboardInterrupt:
        log.debug("Command canceled")
    except exceptions.UncommittedChanges as exception:
        _show_error(exception)
        exit_message = (
            "Run again with --force/--force-interactive to discard changes "
            "or '--skip-changes' to skip this dependency"
        )
    except exceptions.ScriptFailure as exception:
        _show_error(exception)
        exit_message = "Run again with '--force' to ignore script errors"
    except exceptions.InvalidConfig as exception:
        _show_error(exception)
        exit_message = "Adapt config and run again"
    finally:
        if exit_message:
            common.show(exit_message, color='message')
            common.newline()

if not self.link:
            return

        log.info("Creating a symbolic link...")

        target = os.path.join(root, self.link)
        source = os.path.relpath(os.getcwd(), os.path.dirname(target))

        if os.path.islink(target):
            os.remove(target)
        elif os.path.exists(target):
            if force:
                shell.rm(target)
            else:
                msg = "Preexisting link location at {}".format(target)
                raise exceptions.UncommittedChanges(msg)

        shell.ln(source, target)