The plural rule defined for Brazilian Portuguese (in the file /resources/mediawiki.language/languages/pt-br.js, created on r75486) is incorrect, since zero should be considered plural.
The same problem was previously fixed in some other places of MW code, as you can see in the bugs/revs linked below:
- Bug 23707 / r67049
- Bug 25507 / r74712
Version: unspecified
Severity: normal