Update merge from 2.7: s/basetring/str
diff --git a/Lib/argparse.py b/Lib/argparse.py
index e2677f8..eb894ca 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1957,7 +1957,7 @@
# twice (which may fail) if the argument was given, but
# only if it was defined already in the namespace
if (action.default is not None and
- isinstance(action.default, basestring) and
+ isinstance(action.default, str) and
hasattr(namespace, action.dest) and
action.default is getattr(namespace, action.dest)):
setattr(namespace, action.dest,