R1:d0b5dac36b87

Make cluster repositories more chatty

Summary:
Ref T10860. At least in Git over SSH, we can freely echo a bunch of stuff to stderr and Git will print it to the console, so we can tell users what's going on.

This should make debugging, etc., easier. We could tone this down a little bit once things are more stable if it's a little too chatty.

Test Plan:
```
$ echo D >> record && git commit -am D && git push
[master ca5efff] D
1 file changed, 1 insertion(+)
# Push received by "local001.phacility.net"…