compiling code including parallel assignment

I observed

(%i1) foo():= [a,b]:[1,2]$
(%i2) compile(foo);
Dubious first LHS argument to ":"
[a,b]
Compiling C:/DOKUME~1/VANNEK~1/LOKALE~1/Temp/gazonk_1500_0.lsp.
End of Pass 1.  
End of Pass 2.  
OPTIMIZE levels: Safety=2, Space=3, Speed=3
Finished compiling C:/DOKUME~1/VANNEK~1/LOKALE~1/Temp/gazonk_1500_0.lsp.
(%o2)                                [foo]

I do not find anything dubious here. I guess this message doesn't take into account that 
since version 5.1x.0 parallel assignment is possible in Maxima. 

Comments?

Volker van Nek