Author: beau
Description:
There is something wrong with diff function for abusefilter. In the provided URL bot added one interwiki link (one line), but from abusefilter point of view it looks like the whole content of the page was replaced.
Version: unspecified
Severity: major
URL: http://pl.wikipedia.org/w/index.php?title=Specjalna:Rejestr_nadu%C5%BCy%C4%87&details=14746
beau wrote:
The diff shown at the top of the page and the value of edit_diff do not match.
alexsm333 wrote:
Sometimes added_lines and removed_lines both contain one unchanged line from above. (As a result, edit_diff variable is wrong as well.)
Example: [[Special:AbuseFilter/examine/327603336]]; diff: http://en.wikipedia.org/w/index.php?diff=318457689
This actually happens quite a lot (at least on ru.wp), leading to false positives and forcing me to make extra checks on old_wikitext. Bumping severity to major.
I don't have access to URL in beau's post, but I suspect it's the same behaviour.
alexsm333 wrote:
Update: looks like the unchanged line above is always included into added_lines and removed_lines whenever user makes changes to the end of the page.
Although technically AbuseFilter might be right (linebreak \n is indeed added to or removed from the "unchanged line"), this is clearly not the behaviour expected by filters maintainers.
bug 20851 looks similar to this one.