resume pkg fetch downloads?

[Jeffrey Bouquet]

pkg is downloading a large llvm39 file, but times out. (25  minutes > 9 left > quits) 
multiple times...

The destination, final, is a file and symlink, as we know.

I wget-downloaded the file, but pkg install erased it immediately
and began re-downloading anew.
Is there an equivalent series of commands or a feature planned
equivalent to
wget -c -nd (for package fetch and/or install) so an
interrupted download will resume where it left off?  or a series of commands
that will place the wget-retrieved file where it will appear to pkg as being
already present in the /../cache/pkg [or wherever it is set] subdirectory?

Could be useful in the years to come...