Solo opening parenthesis in block comment not interpreted properly in cling

When running an unnamed macro in ROOT6, if one includes an opening parenthesis in a block comment and not a closing one, cling issues an error.
e.g.

{

    /*

     * :(

     */

    cout << "ROOT" << endl;

}

When run in 6.02/05, it causes the error:

root [0]

Processing smiley.C...

Error in cling::MetaProcessor: file smiley.C is incomplete (missing parenthesis or similar)!

root [1] .q

This runs fine in ROOT5 however (tested on 5.34/30).

Note that cling doesn't have an issue with the closing parenthesis [i.e. :) ], nor does it mind a solo "(" in a single line comment, e.g.

{

    // :(

    cout << "I work fine" << endl;

}