[PATCH 0 of 1 RFC] possible fix for issue 2993 (alias shadowing)

[Augie Fackler]

I'm not sure this is actually /correct/ based on my reading of the
code, but I don't break any existing alias tests and it fixes the new
test I added.

I'm not quire sure what the remaining client of aliasdef.cmd is doing
(line 362 or so of dispatch.py). It seems like that might be correctly
changed to aliasdef.name as well, but I wanted to ask what everyone
else thought.