Verify pathRotateKey rotates properly

[kula]

vault-plugin-secrets-backblazeb2/plugin/path_config_rotate.go

Lines 109 to 113 in 3e8eb2c

	client, err = b.getB2Client(ctx, req.Storage)
	if err != nil {
	return nil, errwrap.Wrapf("Failed to create new b2client: {{err}}", err)
	}
	b.client = client

1. Is this safe while not holding the client lock?
2. Do we actually force a new client here --- at this point, b.client isn't nil, so getB2Client should just return the current client....