Last modified: 2014-10-22 20:58:56 UTC
If you go to Wikipedia and search for ||, you get an error: "An error has occurred while searching: The search backend returned an error: ". This only seems to affect Wikipedia - I am unable to reproduce this on other WikiMedia sites.
Happens here as well. Also occurs on Commons: https://commons.wikimedia.org/w/index.php?search=||&title=Special%3ASearch&go=Go Unable to reproduce on Wikidata, Wiktionary, Meta, Wikivoyage, or Wikiquote.
No problem with new CirrusSearch backend: https://commons.wikimedia.org/w/index.php?search=||&title=Special%3ASearch&go=Go&srbackend=CirrusSearch Hence lowest priority and very likely WONTFIX.
Its and lsearchd problem. Cirrus doesn't complain about the ||. We'll restart the march off lsearchd soon so this'll go away with that.
*** This bug has been marked as a duplicate of bug 66259 ***