rest_framework.templatetags.rest_framework is non-conditionally importing markdown.

from markdown.extensions.fenced_code import FencedBlockPreprocessor

from rest_framework.compat import (
    NoReverseMatch, markdown, reverse, template_render
)

https://github.com/tomchristie/django-rest-framework/blob/master/rest_framework/templatetags/rest_framework.py#L12-L16

As per the compat import markdown has previously been an optional dependency. It's still listed as an optional requirement

Without markdown installed, the template tags can no longer be imported. cf carltongibson/django-filter#658

Markdown either needs to be declared required or a work around is needed.