Bug 10900 - Follow up, since more has been added to master

Bug 10900 - Follow up, since more has been added to master

Booksellers.t and Koha_template_plugin_Branches.t both had
function calls to ::set_userenv added to them. This patch handles
those additions.

TEST PLAN
---------
1) Branch a new git branch
2) prove -v t/db_dependent/Bookseller.t
   -- It should work.
3) prove -v t/db_dependent/Koha_template_plugin_Branches.t
   -- It should work.
4) Apply only the first patch.
5) Repeat steps 2 and 3.
   -- They should both FAIL!
6) Apply the second patch as well.
7) Repeat steps 2 and 3.
   -- The should both work.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>