use cached git config

pkg/commands/git_config/fake_git_config.go

@@ -0,0 +1,22 @@
+package git_config
+
+type FakeGitConfig struct {
+	mockResponses map[string]string
+}
+
+func NewFakeGitConfig(mockResponses map[string]string) *FakeGitConfig {
+	return &FakeGitConfig{
+		mockResponses: mockResponses,
+	}
+}
+
+func (self *FakeGitConfig) Get(key string) string {
+	if self.mockResponses == nil {
+		return ""
+	}
+	return self.mockResponses[key]
+}
+
+func (self *FakeGitConfig) GetBool(key string) bool {
+	return isTruthy(self.Get(key))
+}