Re: Add a "git-describe" command

Linus Torvalds [off-list ref] writes:

The problem is not that it generates GIT_VERSION wrong. The problem is 
two-fold:
 - it should notice when "git-describe" doesn't exist, and fall back on 
   the old less-than-descriptive behaviour
 - it doesn't do dependencies correctly (ie it should now make "git" 
   depend on the version number, but it doesn't, so it doesn't re-build 
   git after a commit/pull)

but at least it shows the _idea_ of using git-describe.

With this I get

	[torvalds@g5 git]$ git --version
	git version v1.0.4-g6e9961d6

which I think is better than "1.0.GIT" which doesn't say anything about 
what the _actual_ version was.

I do not think 1.0.GIT is a good name either, so obviously there
is a room for improvement.

One problem with git-describe is that getting tags is a concious
user action, and you need to do "git fetch --tags" from time to
time in order to see the v1.0.4-g6e9961d6 name.  It could well
say v1.0.3-g6649c466 if the end user has built on top of
otherwise fully up-to-date maint branch without fetching v1.0.4
nor v1.0.5 tags, so when we learn that the v1.0.3-g6649c466 does
not work for an end-user, it would not help us to look for
regression between v1.0.3 and v1.0.4.  All it tells us is that
it is not older than v1.0.3, and it may well be the v1.0.5
without any local modification.