Fix premature removal of tmpdir in install_br

Fix premature removal of tmpdir in install_br

When tmpdir is removed in install_br called from build_rpm, subsequent
rpmbuild -bb in build_rpm can fail due to not existent TMPDIR directory
for %patchset macro. For example building of vim.spec fails prints
errors:

rpm: sh: can't create /home/users/builder/rpm/BUILD/vim/tmp/__ps1:
No such file or directory
rpm: sh: can't create /home/users/builder/rpm/BUILD/vim/tmp/__ps2:
No such file or directory
paste: /home/users/builder/rpm/BUILD/vim/tmp/__ps1: No such file or
directory