fix autocompletion for new locations

When complete is installed in /usr/share or /usr/lib64, the last test
command (/usr/lib) fails and causes whole osc automcompletion to fail.

Fix it by adding a 'return' to the former two -- if they succeed.

contrib/complete.sh

@@ -1,6 +1,6 @@
 test -z "$BASH_VERSION" && return
 complete -o default _nullcommand >/dev/null 2>&1 || return
 complete -r _nullcommand >/dev/null 2>&1         || return
-test -s /usr/share/osc/complete && complete -o default -C /usr/share/osc/complete osc
-test -s /usr/lib64/osc/complete && complete -o default -C /usr/lib64/osc/complete osc
+test -s /usr/share/osc/complete && complete -o default -C /usr/share/osc/complete osc && return
+test -s /usr/lib64/osc/complete && complete -o default -C /usr/lib64/osc/complete osc && return
 test -s /usr/lib/osc/complete   && complete -o default -C /usr/lib/osc/complete osc