[perl #121061] named @-siggiled capture explodes when it aliases a positional capture

[Christian Bartolomaeus via RT]

All these examples work now:

$ perl6 -e 'say "a" ~~ /@<from>=(.)*/'
｢a｣
 from => ｢a｣

$ perl6 -e 'say "a" ~~ /$<from>=(.)*/'
｢a｣
 from => ｢a｣

$ perl6 -e 'say "a" ~~ /@<from>=(.)+/'
｢a｣
 from => ｢a｣

$ perl6 -e 'say "a" ~~ /@<from>=[.]+/'
｢a｣
 from => ｢a｣

I added tests for the previously failing evaluations to 
S05-capture/array-alias.t (commit 
https://github.com/perl6/roast/commit/cd2f27032f).

I'm closing this ticket as 'resolved'.