eZ Publish does not return the section id on $module_result.* in content/edit view (and diff, history and versionview).
I created a patch to fix this and reported it here: http://issues.ez.no/IssueView.php?Id=13494&activeItem=1
Feel free to test and vote.
If you want to work around it you can override the pagelayout and take the section id from the current node / object.