Delete dependencies when deleting a repository (#10608)

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>

models/repo.go

@@ -1520,6 +1520,18 @@ func DeleteRepository(doer *User, uid, repoID int64) error {
 		return err
 	}
 
+	// Dependencies for issues in this repository
+	if _, err = sess.In("issue_id", deleteCond).
+		Delete(&IssueDependency{}); err != nil {
+		return err
+	}
+
+	// Delete dependencies for issues in other repositories
+	if _, err = sess.In("dependency_id", deleteCond).
+		Delete(&IssueDependency{}); err != nil {
+		return err
+	}
+
 	if _, err = sess.In("issue_id", deleteCond).
 		Delete(&IssueUser{}); err != nil {
 		return err