reset: give better reflog messages

The reset command creates its reflog entry from argv. However, it does so after having run parse_options, which means the only thing left in argv is any non-option arguments. Thus you would end up with confusing reflog entries like: $ git reset --hard HEAD^ $ git reset --soft HEAD@{1} $ git log -2 -g --oneline 8e46cad HEAD@{0}: HEAD@{1}: updating HEAD 1eb9486 HEAD@{1}: HEAD^: updating HEAD However, we must also consider that some scripts may set GIT_REFLOG_ACTION before calling reset, and we need to show their reflog action (with our text appended). For example: rebase -i (squash): updating HEAD On top of that, we also set the ORIG_HEAD reflog action (even though it doesn't generally exist). In that case, the reset argument is somewhat meaningless, as it has nothing to do with what's in ORIG_HEAD. This patch changes the reset reflog code to show: $GIT_REFLOG_ACTION: updating {HEAD,ORIG_HEAD} as before, but only if GIT_REFLOG_ACTION is set. Otherwise, show: reset: moving to $rev for HEAD, and: reset: updating ORIG_HEAD for ORIG_HEAD (this is still somewhat superfluous, since we are in the ORIG_HEAD reflog, obviously, but at least we now mention which command was used to update it). While we're at it, we can clean up the code a bit: - Use strbufs to make the message. - Use the "rev" parameter instead of showing all options. This makes more sense, since it is the only thing impacting the writing of the ref. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>