Unlink before rename (for NT).

Tools/scripts/ftpmirror.py

@@ -197,6 +197,10 @@ def mirrorsubdir(f, localdir):
 		fp.close()
 		if fp1 != fp:
 			fp1.close()
+		try:
+			os.unlink(fullname)
+		except os.error:
+			pass		# Ignore the error
 		try:
 			os.rename(tempname, fullname)
 		except os.error, msg: