using oldest date when squashing commits

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

moin,

during interactive rebasing, i sometimes find it necessary to move a 
hunk from one commit to a later one in the branch. now, if that hunk 
cannot be re-ordered with the later commit due to conflicting with it, 
it becomes necessary to squash the later commit onto a temporary commit 
created from the extracted hunk, not the other way around (or using a 
stash). unfortunately, this causes the author date of the later commit 
to be reset, which can rather seriously falsify the date if the branch 
is long-lived.

i know how to manually work around that, but that's not exactly user 
friendly.

my first thought was to create an --oldest-date option (essentially 
complementary to --ignore-date).

but i wonder whether it even needs to be an option? why would anyone not 
want that behavior, unless they are explicitly resetting the date 
anyway?

thanks