Can't combine math and custom filter

[mdaeron]

This may be a bug, or just me doing it wrong, but I don't know which.

Problem Description

I am able to implement custom filters to my docstrings using pdoc.render.env.filters, but these filters stop working if I ask for math mode.

Steps to reproduce the behavior:

1. Create following module file hello.py:

"""
foo bar baz
"""

def foo():
	"""
	foo bar baz
	"""
	return 0

2. Create following script make_doc.py to generate documentation:

import pdoc
print(pdoc.__version__) # prints out "15.0.1"

def myfilter(txt):
	out = txt.replace('foo', 'FoO')
	return out

pdoc.render.env.filters['myfilter'] = myfilter
pdoc.render.configure(template_directory = 'pdoc_templates')
# pdoc.render.configure(math = True)

with open('index.html', 'w') as fid:
	fid.write(pdoc.pdoc('hello'))

3. Create pdoc_templates directory with the following files:

• math.html.jinja2, copied from source with no modifications
• module.html.jinja2 with the following contents:

{% extends "default/module.html.jinja2" %}
{% macro docstring(var) %}
    {% if var.docstring %}
        <div class="docstring">{{ var.docstring | to_markdown | myfilter | to_html | linkify(namespace=var.qualname) }}</div>
    {% endif %}
{% endmacro %}

4. Run make_doc.py and check the output, which uses FoO instead of foo, as intended.
5. Uncomment the line in make_doc.py with math = True.
6. Run make_doc.py again. The output now uses fooeverywhere, implying that myfilter was ignored.

System Information

15.0.1