These changes involved a new reference to the file simpletransform.py, which was modified in rev 9635. However, this modification does not relate to either dxf or hpgl. Rev 9635 was new code that did not involve any changes to existing code.
Having said that, I know absolutely nothing at all about how backporting works, so perhaps someone else can make a better judgement.
yes, I think it would be safe to backport these files. The changes would affect the files
dxf_outlines.py rev 9675
dxf_templates.py rev 9675
hpgl_output.py rev 9689
These changes involved a new reference to the file simpletransform.py, which was modified in rev 9635. However, this modification does not relate to either dxf or hpgl. Rev 9635 was new code that did not involve any changes to existing code.
Having said that, I know absolutely nothing at all about how backporting works, so perhaps someone else can make a better judgement.