Aliasing assignment-ish words (aliases[x=y]=z)

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

    1	$ zsh -f
    2	% aliases[x=y]=z 
    3	% alias -L 
    4	alias run-help=man
    5	alias which-command=whence
    6	alias 'x=y'=z
    7	% which x=y 
    8	x=y: aliased to z
    9	% x=y
   10	% echo $+x
   11	1
   12	% 

Shouldn't line 9 have interpreted the word 'x=y' as an alias?  Or
perhaps line 2 should have signaled an error.

Also, the 'alias -L' output for that alias won't work as the code
producing the output intended.