Some extra info:
Output on all releases (not a regression because the output was always wrong):
https://gist.github.com/b4b27b8088a230a6051d634dc7b2d13e
The change in behavior happened in (2017-03-21)
https://github.com/rakudo/rakudo/commit/16f950b30572e0fa584ddfab1e84e5ef0ca5dfc9
Which links
# New Ticket Created by Nick Wellnhofer
# Please include the string: [perl #133017]
# in the subject line of all future correspondence about this issue.
# https://rt.perl.org/Ticket/Display.html?id=133017 >
When using a reduction operator with the "intermediate results" option
combined with
