…TED_WITH request header set (file content rather than the file itself was being passed).
If you don't check for the existence of the property, the upgrade results in an error (Module collective.quickupload.upgrades.upgrades, line 25, in v3_v4 - Module OFS.PropertyManager, line 184, in _setProperty - BadRequest: Invalid or duplicate property id)
…oaded. This already happens automatically for Archetypes in processForm.
…ad of imports for better performance.
This fixes configuration panel after 1.6.1.