Behaviour change on =(<<<herestring) ?

["Daniel Shahaf" <d.s@xxxxxxxxxxxxxxxxxx>]

Consider:

$ Src/zsh -fc 'xxd =(<<<foo)' 
00000000: 666f 6f0a                                foo.
$ zsh-5.9 -fc 'xxd =(<<<foo)' 
00000000: 666f 6f0a                                foo.
$ zsh-5.8 -fc 'xxd =(<<<foo)' 
00000000: 666f 6f                                  foo.
$ 

For comparison, «zsh -fc 'xxd <<<foo'» does produce a newline under
the old version, while «zsh -fc 'xxd =(print -rn foo)'» doesn't
produce a newline even under the new version, so I'm guessing the
behaviour of «<<<» inside «=(…)» specifically changed at some point
between 5.8 and 5.9.

Should this be added to the list of incompatible changes in README?

I found this because one of my scripts broke.

Cheers,

Daniel