[PATCH] Wrap completions in `type git' conditional statement.

Hello,

I don't know if this has come up before (I didn't notice in a casual grep of git log), but attached is a little patch to wrap the bash completion script in a `type git' check.

From the patch header:
--
The onus for checking if a command exists before loading its completions
properly falls on individual completion files since they are normally
sourced from a completions directory (e.g. source /etc/bash_completion.d/*),
or perhaps from a single file concatenated from other completion files.

Also, this is standard practice with other bash-completion scripts.
--


Cheers,
Sung Pae