Now that server version numbers can use the new 'git describe' format, logic in packaging scripts for detecting whether packages are nightlies or not is incorrect.

This code checks if the version ends in a hyphen -
https://github.com/mongodb/mongo/blob/fbb8433c210c2a028fad3524ad6c87817ccff0d8/buildscripts/packager.py#L57-L64

And this code uses that to determine whether to use the release series as the package repo directory or whether to put the package in the "testing" repo directory which should have all RC's and nightlies -
https://github.com/mongodb/mongo/blob/fbb8433c210c2a028fad3524ad6c87817ccff0d8/buildscripts/packager.py#L167-L170