[perl #130527] [BUG] Override of internal character class in grammar won't combine with other character classes

[via RT]

# New Ticket Created by  Ron Schmidt 
# Please include the string:  [perl #130527]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=130527 >


Override of internal character class in gramma won't combine with other
character classes: 

grammar g{
    token alpha {<[2]>};
    token alpha1 {<[2]>};      # same as alpha but without internal car
class conflict
    token beta { <[q]> };
    token delta {<+alpha +beta>};
    token delta1 {<+alpha>};
    token delta2 {<+alpha1 +beta>}
}
say so "2" ~~ /<g::delta1>/;   # OK
say so "2" ~~ /<g::delta2>/;   # OK
say so "2" ~~ /<g::delta>/;    # think wrong - should be true
say so "a" ~~ /<g::delta>/;    # true probably wrong but maybe
understandable