bug#17939: Passing '-p ~/.guix-profile' to 'guix package'

[Taylan Ulrich Bayirli/Kammer]

When I run 'guix package -p ~/.guix-profile ...' I would expect it to
do the same thing as without the '-p ~/.guix-profile', but it doesn't
follow the immediate symlink, changing ~/.guix-profile to point to
e.g. ~/.guix-profile-1-link, and creating that one as a link to
/gnu/store/...-profile.  (Normally it only does that to
$localstatedir/guix/profiles/per-user/$user/guix-profile.)

Perhaps my expectation is wrong because Guix doesn't "know" about the
"trick" of having a ~/.guix-profile symlink to the canonical per-user
profile symlink in $localstatedir/...

As a general solution, Guix could follow all but the last two(?)
symlinks in the symlink chain started by the -p argument.  Don't know
if that's a good solution.

Thoughts?

Taylan