Fix closes issue12438 - idlelib.PyShell's showformatwarning method was passing an incorrect arg.
diff --git a/Lib/idlelib/PyShell.py b/Lib/idlelib/PyShell.py
index 06c8bba..834805e 100644
--- a/Lib/idlelib/PyShell.py
+++ b/Lib/idlelib/PyShell.py
@@ -59,7 +59,7 @@
file = warning_stream
try:
file.write(warnings.formatwarning(message, category, filename,
- lineno, file=file, line=line))
+ lineno, line=line))
except IOError:
pass ## file (probably __stderr__) is invalid, warning dropped.
warnings.showwarning = idle_showwarning