Don't fail with nonexistent files

When the script does not exist, because it was not generated due to some
configure switch or environmental condition, don't try to check if it
gets renamed. That would fail even when the situation is completely OK
and expected.

src/bin/tests/process_rename_test.py.in

@@ -25,6 +25,11 @@ class TestRename(unittest.TestCase):
     def __scan(self, directory, script, fun):
         # Scan one script if it contains call to the renaming function
         filename = os.path.join(directory, script)
+        if not os.path.exists(filename):
+            # We either didn't compile it yet or it is not compiled based
+            # on some environmental condition. That is OK, we don't want
+            # to break on that.
+            return
         with open(filename) as f:
             data = ''.join(f.readlines())
         prettyname = 'src' + filename[filename.rfind('../') + 2:]