https://bugzilla.redhat.com/show_bug.cgi?id=1433749
--- Comment #4 from Dominik 'Rathann' Mierzejewski dominik@greysector.net --- You should use install with -p option (in addition to -m) for installing files into their destination location in %install. Otherwise they get package-build-time timestamps.
https://fedoraproject.org/wiki/Packaging:Guidelines#Timestamps