[perl #131704] Can't use unknown trait 'is export' in a regex declaration

[via RT]

# New Ticket Created by  Lloyd Fournier 
# Please include the string:  [perl #131704]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=131704 >


perl6 -e 'constant $foo is export = /foo/;'

&is-export seems to be being called on the regex rather than the variable??