svn dcommit: where happens the writing of the timestamp?

Hi,

Could someone please show me, where the timestamp is rewritten in the code, so that I could change it and compile a local copy of git, that fits my needs? Perhaps I could even create a patch, that implements "--preserve-timestamps" and send it back.

I've already searched in git-svn.perl but without success... :(

TIA for any hints,

           Peter