auto gc

Hi,

I've noticed that recent git versions, in a supposedly helpful fashion, run garbage collection automatically after a pull if it deems it necessary:

[...]
Resolving 556 deltas...
 100% (556/556) done
Updating 9418d5d..99fee6d
Fast forward
Packing your repository for optimum performance. You may also
run "git gc" manually. See "git help gc" for more information.
Generating pack...
[...]

This is extremely annoying behaviour! If I'm on battery or just in a bit of a hurry, I defeinitely don't want git second guessing me and deciding that it's time to run git gc.

I'd suggest just printing a hint that running git gc would increase performance, doing it automatically is definitely bad style (even more so when then yet again changed git refs layout even breaks old scripts, when git gc has run).