Join for OAauth tags results in duplicate revisions when multiple tags are queried

[ragesoss]

For example:

https://wikiedudashboard.toolforge.org/revisions.php?db=enwiki&usernames[]=Petra+Sen&oauth_tags[]=OAuth+CID%3A+252&oauth_tags[]=OAuth+CID%3A+212&oauth_tags[]=OAuth+CID%3A+542&start=20160920003430&end=20160922003430

vs

https://wikiedudashboard.toolforge.org/revisions.php?db=enwiki&usernames[]=Petra+Sen&oauth_tags[]=OAuth+CID%3A+542&start=20160920003430&end=20160922003430

We should either fix the query so it works as intended (returning system: true for each revision that has any of the specified tags), or change it to only use one tag.