Fixed error when non-superuser tries to create a top-level page

[damianmoore]

When a non-superuser that had the correct page-level permissions tried to create a 'New Page' from the CMS toolbar, I was getting the error invalid literal for int() with base 10: '' appear in the sidebar. The user could, however, create a new top-level page from within the admin.

I tracked the problem down to 2 places in the cms codebase. cms_toolbar.py add_page_menu() method of PageToolbar. Where the URL is being generated for the 'New Page' link target is set to self.page.parent_id or '', which at the top level means '' empty string.

url="%s?language=%s&edit=1&target=%s&position=last-child" % (
    reverse("admin:cms_page_add"),
    self.toolbar.language,
    self.page.parent_id or ''
)

Then in utils/permissions.py has_page_add_permission() function, target gets extracted from request.GET

target = request.GET.get('target', None)

so target is an empty string. It's not None so passes the if statement test. Then it tries to get a Page object using empty string as the pk:

page = Page.objects.get(pk=target)

Which gives the error invalid literal for int() with base 10: ''. Being less strict about the checking of target means cms doesn't try to make it a sub-page.

[coveralls]

Coverage decreased (-0.1%) to 87.997% when pulling dea80fe on damianmoore:fix_for_non_superuser_adding_top_level_page into 99c0a1e on divio:develop.