setup-session.sh: use libtest.sh for setup

The libtest.sh script is aware of whether a tmpdir needs to be created
or not for the test. Make use of this in setup-session.sh so that we're
sure we're in the right directory before creating the sysroot dir.

tests/libtest.sh

@@ -19,17 +19,22 @@
 
 SRCDIR=$(dirname $0)
 _cleanup_tmpdir () {
-    if test -f ${test_tmpdir}.test; then
-	rm ${test_tmpdir} -rf
+    if test -f ${test_tmpdir}/.test; then
+        rm ${test_tmpdir} -rf
     fi
 }
+
+# If we're running as a local test (i.e. through `make check`), then
+# UNINSTALLEDTESTS=1. Otherwise (i.e. as an installed test), it's undefined, in
+# which case we're already in a tmpdir.
 if test -n "${UNINSTALLEDTESTS:-}"; then
    test_tmpdir=$(mktemp -d test.XXXXXX)
    touch ${test_tmpdir}/.test
    trap _cleanup_tmpdir EXIT
    cd ${test_tmpdir}
    export PATH=${builddir}:${PATH}
-fi   
+fi
+
 test_tmpdir=$(pwd)
 
 export G_DEBUG=fatal-warnings

tests/setup-session.sh.in

@@ -19,12 +19,14 @@
 # Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 # Boston, MA 02111-1307, USA.
 
-test_tmpdir=$(pwd)
+set -e
+
+. $(dirname $0)/libtest.sh
 
 exec_binary="@LIBEXECDIR@/rpm-ostreed"
 
-mkdir sysroot
-mkdir session-services
+mkdir -p sysroot
+mkdir -p session-services
 
 # Create a busconfig file with a custom <servicedir>
 cat > session.conf <<EOF