Verify list len before use it with IN (#3423)

models/org.go

@@ -414,9 +414,12 @@ func RemoveOrgUser(orgID, userID int64) error {
 			return err
 		}
 	}
+
+	if len(repoIDs) > 0 {
 		if _, err = sess.Where("user_id = ?", user.ID).In("repo_id", repoIDs).Delete(new(Access)); err != nil {
 			return err
 		}
+	}
 
 	// Delete member in his/her teams.
 	teams, err := getUserTeams(sess, org.ID, user.ID)