[Cython] remove timestamps from generated source files

[Julian Taylor]

Hi,
Cython currently places timestamps into all its generated C source files.
This may be ok for developers who normally only rebuild files they
changed anyway but it is a major annoyance for distribution packagers
who often have to rebuild software from scratch including re-cythonizing.
The reason this is annoying is that the adding of timestamps breaks
caching of compiler results e.g. with ccache. Due to the size of the
generated files recompiling the full sources normally takes a large
fraction of the build time of packages.

I'm not sure what purpose the timestamps really serve, the version
number also included should be sufficient information in order to deduce
its origin.

Would it be possible to change Cython to stop putting timestamps into
the source?
I would also be happy if the granularity is reduced from seconds to
hours/days or an non-default option to disable it (e.g. an environment
variable).


Additionally I think it might be useful to have a vendor id added to the
version number added to the source files. This would allow easier origin
tracking of files created with distribution patched versions of Cython.
E.g. if Debian patches 0.20 of Cython it puts in

 Generated by Cython 0.20 (Debian revision 3)

Where the vendor id is added via a Distribution patch of the package and
none is emitted for upstream builds.
(CC. Debian maintainer of Cython for comments)

Cheers,
Julian Taylor