Arch Linux: Denial of service (CVE-2019-14232)

If ``django.utils.text.Truncator``'s ``chars()`` and ``words()`` methods were passed the ``html=True`` argument, they were extremely slow to evaluate certain inputs due to a catastrophic backtracking vulnerability in a regular expression. The ``chars()`` and ``words()`` methods are used to implement the ``truncatechars_html`` and ``truncatewords_html`` template filters, which were thus vulnerable. The regular expressions used by ``Truncator`` have been simplified in order to avoid potential backtracking issues. As a consequence, trailing punctuation may now at times be included in the truncated output.