Author date:
git commit --amend --date="Wed Feb 16 14:00 2011 +0100"
Commit date:
GIT_COMMITTER_DATE="Wed Feb 16 14:00 2011 +0100" git commit --amend
You've got to love git.
(source)
A piggy bank of commands, fixes, succinct reviews, some mini articles and technical opinions from a (mostly) Perl developer.