Searching for two numbers with less than 5 digits separated by a colon (like 1234:1234) takes you to contribution list for that username (Special:Contributions/1234:1234). This occurs when using either search field and go button (but not search button), or when using links or urls like [[Special:Search/123:123]].
If one or both numbers have at least 5 digits, searching appears to work correctly.
Version: 1.16.x
Severity: normal
URL: http://sv.wikipedia.org/wiki/Special:Search/1:2