htmldocck: fix a bug in relative paths / globs

This bug only shows up when you run htmldocck in a directory other
than outdir, and also use globs. Never happened before, which is
why we're only seeing it now.

Author: notriddle

src/etc/htmldocck.py

@@ -247,7 +247,7 @@ def get_absolute_path(self, path):
             paths = list(Path(self.root).glob(path))
             if len(paths) != 1:
                 raise FailedCheck("glob path does not resolve to one file")
-            path = str(paths[0])
+            return str(paths[0])
         return os.path.join(self.root, path)
 
     def get_file(self, path):