fix interpreting int as second--> nano
The existing behavior was put in place in #4684, looks like wrestling with numpy 1.6 and 1.7 was rough.

Not sure what this merits in the whatsnew, pls advise.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
