get nothing, but require('child_process').exec('git summary --line') will get the right stdout.

var exec = require('child_process').exec
exec('git summary', function(err, stdout) {
    //nothing in here works
})

exec('git summary --line', function(err, stdout) {
    //works fine
    assert(stdout)
})

When I try use node to get the stdout from git summary, I find this strange thing, do not know why.
I hope it can be fixed.
Thanks.