selftest: template: Test existing overlay dir features

Change-Id: Iff1a4dafcbf2193e95b1fb6e5a6712f1bcdd6309
diff --git a/selftest/template_test/mytemplatedir/osmo-bsc.cfg.tmpl b/selftest/template_test/mytemplatedir/osmo-bsc.cfg.tmpl
new file mode 100644
index 0000000..5c9400b
--- /dev/null
+++ b/selftest/template_test/mytemplatedir/osmo-bsc.cfg.tmpl
@@ -0,0 +1 @@
+test-overlay-works-fine ${foo.bar.works}