StripBeforeTransformer not emitting correctly?

[svanschalkwyk]

I have a field such as the one below:

<meta name="p_temp_id">/ip/Bolthouse-Farms-Organics-Premium-Matchstix-Julienne-Carrots-10-oz/44933639</meta>

With the configuration below, I expect "44933639" to be written back to the same field. Instead, the original field value is returned.

<transformer class="com.norconex.importer.handler.transformer.impl.StripBeforeTransformer" inclusive="true" caseSensitive="false">
    <restrictTo caseSensitive="false" field="p_temp_id">.*</restrictTo>
    <stripBeforeRegex>\d{6,}$</stripBeforeRegex>
</transformer>

when: