[perl #129299] [REGEX] Quantified capture group breaks `$/.list`

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# New Ticket Created by  Sam S. 
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When a quantified capture group matched zero times but the overall regex 
matches, then the List returned from `$/.list` stops iterating before the 
corresponding element:

    "ac" ~~ / (a) (b)? (c) /;
    say ($0, $1, $2);         # (｢a｣ Nil ｢c｣)
    say $/.list;              # (｢a｣)
    say $/.list.map({1});     # (1)
    say $/.list.elems;        # 3
    say $/.list[0, 1, 2, 3];  # (｢a｣ (Mu) ｢c｣ Nil

Expected behavior would be for `$/.list;` to return `(｢a｣ Nil ｢c｣)`.

mst++ suggested that maybe an InterationEnd is ending up where it shouldn't be.