fix Bytes submission pb on POST, due to multiple call to field.process_form_value for a same field. In the case of file, stream.read() doesn't return file's data the second time (since the cursor is at the end of the file). Fix this by having a generic process_form_value method that cache field's value in form.formvalues[field] and so _process_form_value is only called once. You should then override that later method on custom fields.

debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/web usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/shared/data usr/share/cubicweb/cubes/shared
debian/tmp/usr/share/cubicweb/cubes/shared/wdoc usr/share/cubicweb/cubes/shared