Christian Franke wrote:
> This could be used to check whether a package is possibly 
> reproducible. Then it could make sense to add a reasonable 
> SOURCE_DATE_EPOCH value to the cygport file.
>
> Example:
>
> $ export SOURCE_DATE_EPOCH=$(date +%s)
>
> $ cygport project.cygport all repro-check
> ...
> *** Info: Build reproducibility test succeeded
>
> $ TZ=UTC cygport project.cygport repro-check
> ...
> *** Info: Build reproducibility test succeeded
>
> $ unset SOURCE_DATE_EPOCH
>
> $ cygport project.cygport repro-check
> ...
> *** ERROR: Build reproducibility test failed
>

An enhanced version of the patch is attached. The build and diff could 
now be run also individually and the diff report includes individual 
files from the packages.

As a side effect, this enables another use case: Check whether changes 
to cygport only change the expected files.

$ cygport project.cygport all repro-check
...
*** Info: Rebuild produced identical packages

$ editor project.cygport
... Change some comments ...

$ cygport project.cygport all repro-diff
...
Differing files found:
! dist/project/project-1.2-3-src.tar.xz
! spkg/project-1.2-3.src/project.cygport

*** ERROR: Rebuild differs from original

-- 
Regards,
Christian