Fix typo during merge from master

Author: johnthagen

src/bootstrap/configure.py

@@ -394,7 +394,7 @@ def configure_section(lines, config):
     if section_key not in sections:
         raise RuntimeError("config key {} not in sections".format(section_key))
 
-    if __key == 'target':
+    if section_key == 'target':
         for target in section_config:
             configure_section(targets[target], section_config[target])
     else: