Convention for help in git commands?

Hi,

is there a commonly accepted way how to handle help messages
in git commands? In git-mv/git-rename, there is a full help
message with description of options when "-h" is given.
This seems to be the Cogito way; git commands seem to be used
to output an one-liner usage only, and rely on the man
page otherwise.

This should be more consistent. Proposal:
* All git commands should react on command line option "-h"
for help, dumping a few lines to stderr, prefixed by "usage:", giving
the command usage without further descriptions. For the usage
output, use the base name of the command, and not the absolute
path to the binary.
* For commands which need at least one argument, the usage
is also printed, if the command is run without argument
* On a error condition, prefix the message with "error:", and
do not print out anything else (like the usage line, or things
produced by the PERL "die", which appends "at scriptname line nn").

Perhaps these things should be done only for commands of the
git lightwight porcelain?

Josef