[perl #77524] Rakudo allows postfix<:> in regexp(?) but STD doesnt

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# New Ticket Created by  Paweł Pabian 
# Please include the string:  [perl #77524]
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[18:54] <bbkr> rakudo: / x:/
[18:54] <p6eval> rakudo 6ccdcd:  ( no output )

[18:54] <bbkr> std: / x:/
[18:54] <p6eval> std 32116: OUTPUT«===SORRY!===␤Unrecognized 
regex metacharacter : (must be quoted to match literally) at /tmp/p4Hf1aN4K8 
line 1:␤------> / x:⏏/␤Check failed␤FAILED 00:01 116m␤»