Proposal for making Multi-Arch:same binNMU-safe

[Helmut Grohne]

Hi Simon,

On Thu, Apr 16, 2026 at 11:02:33AM +0200, Simon Josefsson wrote:
> That all sounds okay, except I don't follow why the final *.deb has to
> have the SOURCE_DATE_EPOCH modtime too?

The modification time we were talking about was the one of installed
files. I don't know whether the .deb's modification time is clamped nor
am I aware of any problems around its modification time.

> What would break if you went back to setting SOURCE_DATE_EPOCH to the
> last non-binNMU debian/changelog source timestamp entry AND set the
> modtime of the resulting *.deb's to the timestamp of the binNMU
> changelog timestamp?

Ian's backup system.

Installed files would be changing content while not changing their
modification time. The backup system would treat them as unchanged and
skip them. His backup is inconsistent as a result.

Helmut