[RFC] pull/fetch rename

Hi all,

While everyone is busy in two other UI threads, I figured I might as well toss up another (probably) controversial topic.

Especially on IRC, we see many people who are some combination of misunderstanding, misusing or overusing git-pull. I figure this is the result of several factors, notably

a) pull/push are not symmetric,

b) guides/tutorials recommend pull for situations where they
   shouldn't,

c) people blindly fire commands at git.

While the latter two are probably hopeless, I find (a) rather annoying. It breaks everyone's intuition of git-pull when they first see it. (I know that BK has a pull that also merges, but I gather from the manual [never used it] that you cannot do the equivalent of git-fetch in BK.)

As you probably guessed by now, here is an idea for a very aggressive transition plan to address (a) in four phases:

1. git-fetch gets options --merge/-m and --rebase that make it behave
   like (current) git-pull, but requiring explicit arguments.
   git-pull gets a new option --merge (-m) that only enforces presence
   of arguments.

2. git-pull refuses to do any work unless given either --merge or
   --rebase.  Deprecation warnings for this start at the same time as
   (1.).

3. git-pull becomes a synonym for git-fetch.

4. git-fetch gives deprecation warnings that point the user to
   git-pull instead.

(1.) is probably harmless and could be put into any particular release. (2.) obviously breaks everyone's favourite script and needs to fall on a major release. (3.) should be delayed significantly from (2.) to allow time to expose such breakage, and similarly (4.) should be delayed after (3.) (or just ignored, but in any case git-pull would become the preferred spelling).

As you probably noticed, while 'git pull $remote $ref' only needs to be changed to 'git pull --merge $remote $ref', this leaves a gap at the current functionality of 'git pull' without arguments. Björn laid out a nice suggestion for a git-update in

  http://article.gmane.org/gmane.comp.version-control.git/130679

briefly summarised as: git-update would cover what 'git pull' (without arguments) does right now. However, it could also be restricted to fast-forward updates by default (with per-branch configurability as with current git-pull).

Comments?  Flames?  Improvements?