Backporting new minor versions

[Jonathan Nieder <jrnieder@gmail.com>]

Hi backporters,

https://backports.debian.org/Contribute/#index7h3 tells me

  Don't backport minor version changes without any user visible
  changes or bugfixes.

But https://backports.debian.org/Contribute/#index5h3 tells me

  Update your backport when a new version enters testing.

Which is right?  If a new minor version enters testing, should I
backport it or not?  Is the first quote about whether to make a
backport in the first place and the second about when to update the
backport?

Actually, when would this come up?  When does a package bump version
number without changing user-visible behavior?

Thanks,
Jonathan