Change runtest to not expect the program name on stderr (led to trouble with
libtool runtime paths). Adapt add_from_file, and enable test that was disabled
because of this problem.

Add another test inspired by a problem report by Oliver Kaiser;
the test works however, so something must be different.

--HG--
branch : HEAD
diff --git a/regress/add_from_file_twice_duplicate.test b/regress/add_from_file_twice_duplicate.test
new file mode 100644
index 0000000..94528cb
--- /dev/null
+++ b/regress/add_from_file_twice_duplicate.test
@@ -0,0 +1,6 @@
+# add file to zip twice, making duplicate names
+program add_from_file
+return 1
+args testfile.zip testfile.txt testfile.txt
+file testfile.txt testfile.txt testfile.txt
+stderr can't add file `testfile.txt': File already exists