Wikimedia Bugzilla is closed!

[this is on trunk, r95456]
I'm having issues tracking this down.

Upload an image thats a duplicate of some other existed image, do not click ignore warnings. Comes up with the warnings, click submit modified description, then we get:

Warning: preg_match() expects parameter 2 to be string, object given in /var/www/w/phase3/includes/upload/UploadStash.php on line 84

Catchable fatal error: Object of class UploadStashFile could not be converted to string in /var/www/w/phase3/includes/upload/UploadStash.php on line 85

It appears the session key is UploadStashFile instead of a string key like it should be.

Backtrace is:
    * UploadStash.php line 84 calls wfBacktrace()
    * SpecialUpload.php line 957 calls UploadStash->getFile()
    * SpecialUpload.php line 802 calls UploadForm->getDescriptionSection()
    * SpecialUpload.php line 263 calls UploadForm->__construct()
    * SpecialUpload.php line 399 calls SpecialUpload->getUploadForm()
    * SpecialUpload.php line 466 calls SpecialUpload->showUploadWarning()
    * SpecialUpload.php line 202 calls SpecialUpload->processUpload()
    * SpecialPageFactory.php line 469 calls SpecialUpload->execute()
    * Wiki.php line 221 calls SpecialPageFactory::executePath()
    * Wiki.php line 621 calls MediaWiki->performRequest()
    * Wiki.php line 528 calls MediaWiki->main()
    * index.php line 58 calls MediaWiki->run()