commit: Fix symlinking

Fixes #65

bin/commit

@@ -699,6 +699,7 @@ for base, ns, items in sorted(all_exams,key=lambda i:i[1].lectures):
     for path in link_directories:
       print("  creating symlinks in %s"%path)
       for item in items:
+        item=os.path.basename(item)
         try:
           os.symlink(
             os.path.relpath(