Fix undefined variable 'val' in tools/editconf.py (#2137)

Merges #2137.

tools/editconf.py

@@ -136,9 +136,10 @@ while len(input_lines) > 0:
 # Put any settings we didn't see at the end of the file,
 # except settings being cleared.
 for i in range(len(settings)):
-	if (i not in found) and not (not val and erase_setting):
+	if i not in found:
 		name, val = settings[i].split("=", 1)
-		buf += name + delimiter + val + "\n"
+		if not (not val and erase_setting):
+			buf += name + delimiter + val + "\n"
 
 if not testing:
 	# Write out the new file.