Add prototype test that we want to fail, which currently doesn't.
diff --git a/regress/Makefile.am b/regress/Makefile.am
index 61ac8ac..8d25392 100644
--- a/regress/Makefile.am
+++ b/regress/Makefile.am
@@ -132,6 +132,7 @@
 	encoding-cp437-all.test \
 	encoding-utf-8.test \
 	open_filename_duplicate.test \
+	open_filename_duplicate_consistency.test \
 	open_incons.test \
 	torrent-new.test
 
diff --git a/regress/open_filename_duplicate_consistency.test b/regress/open_filename_duplicate_consistency.test
new file mode 100644
index 0000000..a997972
--- /dev/null
+++ b/regress/open_filename_duplicate_consistency.test
@@ -0,0 +1,6 @@
+# zip_open: file opens fine even though same file name appears twice
+program tryopen
+args -c filename_duplicate.zip
+return 0
+file filename_duplicate.zip filename_duplicate.zip filename_duplicate.zip
+stderr some error about a duplicate file name