(bug 64997) Bugfix - Note: self.limit could be -1

Partly revert of https://gerrit.wikimedia.org/r/#/c/130019/
testing of bool(self.limit) is True when it is -1.
We have to check whether self.limit > 0

Change-Id: If25add4c3ba7892416195337d5a79993baf6d0d9