PDF generation doesn't use context processors

As render_to_string only uses the defined context processors if a valid request has been provided, context processors are ignored for PDF generation in background.

added part::backend prio::1 source::customer type::bug labels

changed title from Context processors aren't used by PDF generation to PDF generation doesn't use context processors

assigned to @hansegucker

created merge request !811 (merged) to address this issue

mentioned in merge request !811 (merged)

closed with merge request !811 (merged)

mentioned in commit 459123e3