I just committed code that revamps DISTFILES handling completely.
If really necessary, a distfiles entry may look like
filename{url}
and it will fetch that url from MASTER_SITES into resulting filename.
Of course, it's still a better idea to coerce upstream to have correct
archive names, but this may occasionally prove simpler...
Also, this means the FETCH_CMD is now supposed to work like ftp(1), in
partical support -C -o filename url.
If you have a specific alias that doesn't, well, tough shit. Writing a
small shell script that does the conversion shouldn't be too hard.
(see getopt(1) for starters).
