Don't use 'set_option()' or 'get_option()' method -- direct attribute access,
or getattr/setattr, is all that's needed.
diff --git a/Lib/distutils/command/install_lib.py b/Lib/distutils/command/install_lib.py
index 5740c5e..852e3f6 100644
--- a/Lib/distutils/command/install_lib.py
+++ b/Lib/distutils/command/install_lib.py
@@ -79,7 +79,7 @@
 
         build_cmd = self.find_peer (build_cmd)
         build_files = build_cmd.get_outputs()
-        build_dir = build_cmd.get_option (cmd_option)
+        build_dir = getattr (build_cmd, cmd_option)
 
         prefix_len = len (build_dir) + len (os.sep)
         outputs = []