Historical versions of page templates aren't included in xml during space export

Issue Summary

This is reproducible on Data Center: yes

Steps to Reproduce

1. Create space
2. Go to the space and choose Space tools > Content Tools from the bottom of the sidebar.
3. Choose Templates > Create new template
4. Save your template (more info about template creation could be found here)
5. Make any changes in template and save them again
6. Check that there are two versions of template present in DB:

   select * from pagetemplates where templatename = 'your_template_name'; 

7. Go to Space tools > Content Tools again and choose Export
8. Select XML and press Next
9. Select Full Export and press Export
10. Look at generated XML file and search for objects with class "PageTemplate"

Expected Results

Both current and history version of page template are present.

Actual Results

Only current version of page is present in XML.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available