Bug 11182: (follow-up) fix regression where session branch wasn't initialized

C4::Context->userenv() won't return a valid value until the
user session set up, e.g., via get_template_and_user().  Consequently,
the change introduced by a previous commit for bug 11182 ended
up making it appear that when checking an item that fills a hold
that it always needs to be transferred.

This patch fixes the regression and moves the "no-branch-set" check
to where it belongs.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>