Issue2495: tokenize.untokenize did not insert space between two consecutive string literals:
"" "" => """", which is invalid code.

Will backport
diff --git a/Misc/NEWS b/Misc/NEWS
index ec65705..7264dca 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -76,6 +76,10 @@
 Library
 -------
 
+- Issue #2495: tokenize.untokenize now inserts a space between two consecutive
+  string literals; previously, ["" ""] was rendered as [""""], which is
+  incorrect python code.
+
 - Issue #2248: return the result of the QUIT command. from SMTP.quit().
 
 - Backport of Python 3.0's io module.