Wikimedia Bugzilla is closed!

When previewing a page, if the page transcludes itself in some way, the version of the page from the database is used for this transclusion rather than the version of the page being previewed. Example: Create a page called Template:Foo with this content:
<noinclude>{{Foo|one}}</noinclude>
<includeonly>{{{1}}} two</includeonly>
Save it, then reopen the edit window and change it to the following:
<noinclude>{{Foo|three}}</noinclude>
<includeonly>{{{1}}} four</includeonly>
Upon pressing "Show preview", the expected result is to see "three four", but instead, "three two" is seen.

(Related: If Extension:TemplateSandbox is used, and the template's own name is entered as the page to preview, the result is "one four", although "three four" is still expected.)