[perl #128314] stubbed sub in RHS of constant not being updated

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# New Ticket Created by  Lloyd Fournier 
# Please include the string:  [perl #128314]
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m: sub f {...}; our constant @a = lazy map { f() }, ^Inf; sub f { rand };
say @a[^3]
22:14 <+camelia> rakudo-moar dfbf1e: OUTPUT«Stub code executed␤

grondilu++ for picking this up

Since the RHS of the constant is actually being run at runtime and not
BEGIN the reference to it should not be point to the definition but it's
still executing the sub.