Array Appending Plus Postblits

[dsimcha]

I was browsing through druntime's lifetime.d for an unrelated reason and I
noticed that, when an array is copied for the purpose of appending to it, the
postblits are not called on the new array if it is an array of structs.  Is
there something I'm missing, or is this a bug that somehow noone has noticed
up to this point?