No need to use mimetypes_registry with hard coded name to get mime_type.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@37187 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/PDFDocument.py

@@ -139,8 +139,7 @@ class PDFDocument(Image):
         if not src_mimetype.endswith('png'):
           continue
         content = '%s' % png_data
-        mime_type = getToolByName(self, 'mimetypes_registry').\
-                                    lookupExtension('name.%s' % 'txt')
+        mime_type = 'text/plain'
         if content is not None:
           portal_transforms = getToolByName(self, 'portal_transforms')
           result = portal_transforms.convertToData(mime_type, content,