Why repalloc() != realloc() ?

Hackers,

Is there a reason why repalloc() does not behave the same as realloc?
realloc(NULL, size) behaves the same as malloc(size), and it seems
useful behavior -- I wonder why repalloc() chooses to Assert() against
this exact condition?

I assume this is because the NULL pointer would not know what context it
belongs to, but the obvious answer is CurrentMemoryContext just like
palloc() does.  So there must be another reason.

Can this behavior be changed?

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Para tener más hay que desear menos"