Back quote typo in error messages (?)

Hello everyone,

it's been a couple of days that I keep noticing something (very minor) that my OCD for symmetric things can't really stand.

If you run the following command:

$ git branch --i-dont-exists

you should get:

error: unknown option `i-dont-exists'

Shouldn't the wrong flag be surrounded by two single quotes instead of a back quote and a single quote?

For the sake of completeness, I'm on Mac running Git 2.10.1.

Thanks, Fabrizio