git log use of date format differs between Command Line and script usage.

If you supply a non-standard format to the date configuration for git
log, something like:
[log]
        date = format:%Y-%m-%d %H:%M

then, when you run 'git log' inside a script, or when using gitk (anywhere), it fails on decoding the format.

fatal: unknown date format format: %Y-%m-%d %H:%M

However, that format works correctly on the command line. I do not have a patch to address this issue.

-Shaun