Change user name in Pull Requests

models/pull.go

 	}
 }
 
+func ChangeUsernameInPullRequests(oldUserName, newUserName string) (error) {
+	pr := PullRequest{
+		HeadUserName : newUserName,
+	}
+	_, err := x.Cols("head_user_name").Where("head_user_name = ?", oldUserName).Update(pr)
+	return err
+}
+
 // checkAndUpdateStatus checks if pull request is possible to levaing checking status,
 // and set to be either conflict or mergeable.
 func (pr *PullRequest) checkAndUpdateStatus() {

models/user.go

 		return ErrUserAlreadyExist{newUserName}
 	}
 
+	err = ChangeUsernameInPullRequests(u.LowerName, newUserName)
+	if err != nil {
+		return err
+	}
+
 	return os.Rename(UserPath(u.LowerName), UserPath(newUserName))
 }