json: add more paranoid escaping

mercurial/templatefilters.py

@@ -213,6 +213,7 b' def _uescape(c):'
 _escapes = [
     ('\\', '\\\\'), ('"', '\\"'), ('\t', '\\t'), ('\n', '\\n'),
     ('\r', '\\r'), ('\f', '\\f'), ('\b', '\\b'),
+    ('<', '\\u003c'), ('>', '\\u003e')
 ]
 
 def jsonescape(s):