Add test case for UTF-8 parent config file name

test/191_data/main.cfg

@@ -0,0 +1,18 @@
+
+parent 191_data/parent_ü.cfg
+
+BOX designA
+
+sample
+    A from config file main
+ends
+
+shapes {
+     w ("AAA", "AAA", "AAA")
+}
+
+elastic (
+	w
+)
+
+END designA

test/191_data/parent_ü.cfg

@@ -0,0 +1,15 @@
+BOX designB
+
+sample
+    B from config file parent_ü
+ends
+
+shapes {
+     w ("BBB")
+}
+
+elastic (
+	w
+)
+
+END designB

test/191_unicode_parent_config.txt

@@ -0,0 +1,13 @@
+:DESC
+Reference a design from a parent config defined in a config file with a UTF-8 file name.
+
+:ARGS
+-f 191_data/main.cfg -d designB -p l1 -s x3 -a vc
+:INPUT
+foo
+:OUTPUT-FILTER
+:EXPECTED
+BBB
+BBB foo
+BBB
+:EOF