Use explicit check for python version (see issue #2856)

tools/issue_1999.py

@@ -97,11 +97,9 @@ def process_file(path):
 
   with open(path, 'w', encoding='utf-8') as fp:
     str = "\n".join(result) + "\n"
-    try:
-      # Python 2
+    if sys.version_info.major == 2:
       fp.write(str.decode('utf-8'))
-    except Exception as e:
-      # Python 3
+    else:
       fp.write(str)