Hi,

This was bugging me for other commands I was running (emerge -uDN
world), so I decided to try to write a patch for this.

In the process, I found another blocking bug, which would have broken
the -u flag entirely. Currently, 'sudo -u root whoami' returns '-u',
because of a bug involved with processing leading positional arguments.

I fixed the blocking bug first in a separate patch, and then added a new
parameter for commands like sudo, which would prefer :raw-positional
arguments after the first non flag argument. I'm still not sure if this
is the best name for this idea, so if anyone has a better name I'd be
happy to change it!

this section of eshell seems very important, so I also added some tests,
contained in the second patch. Please let me know if anything seems
wrong, as I didn't understand the code as well as I would have liked.

Commit 1: