Use nanoseconds for cache_key timestamp instead of plain seconds
Merge pull request #3773 from ElMassimo/master

Use nanoseconds for cache_key timestamp instead of plain seconds
Changelog Entry for #3773
User.all.pluck(*multiple) should not compact the result.

When passing multiple fields, and a few fields dont exist, or dont have
data, we should return nil, otherwise the returned arrays will have
different size.

[fixes #3703]