templates: escape NUL bytes in jsonescape (issue4303) stable

templates: escape NUL bytes in jsonescape (issue4303)

It's currently possible for various fields to contain NUL bytes, which
are disallowed in JSON.

--- a/mercurial/templatefilters.py	Thu Jul 03 10:48:37 2014 +0100
+++ b/mercurial/templatefilters.py	Mon Jul 14 12:44:45 2014 -0500
@@ -215,7 +215,7 @@
 _escapes = [
     ('\\', '\\\\'), ('"', '\\"'), ('\t', '\\t'), ('\n', '\\n'),
     ('\r', '\\r'), ('\f', '\\f'), ('\b', '\\b'),
-    ('<', '\\u003c'), ('>', '\\u003e')
+    ('<', '\\u003c'), ('>', '\\u003e'), ('\0', '\\u0000')
 ]
 
 def jsonescape(s):

--- a/tests/test-hgweb-commands.t	Thu Jul 03 10:48:37 2014 +0100
+++ b/tests/test-hgweb-commands.t	Mon Jul 14 12:44:45 2014 -0500
@@ -1436,7 +1436,7 @@
   <script>
   <!-- hide script content
   
-  var data = [["cad8025a2e87", [0, 1], [[0, 0, 1, 3, "FF0000"]], "branch commit with null character: \x00", "test", "1970-01-01", ["unstable", true], ["tip"], ["something"]], ["1d22e65f027e", [0, 1], [[0, 0, 1, 3, ""]], "branch", "test", "1970-01-01", ["stable", true], [], []], ["a4f92ed23982", [0, 1], [[0, 0, 1, 3, ""]], "Added tag 1.0 for changeset 2ef0ac749a14", "test", "1970-01-01", ["default", true], [], []], ["2ef0ac749a14", [0, 1], [], "base", "test", "1970-01-01", ["default", false], ["1.0"], ["anotherthing"]]]; (esc)
+  var data = [["cad8025a2e87", [0, 1], [[0, 0, 1, 3, "FF0000"]], "branch commit with null character: \u0000", "test", "1970-01-01", ["unstable", true], ["tip"], ["something"]], ["1d22e65f027e", [0, 1], [[0, 0, 1, 3, ""]], "branch", "test", "1970-01-01", ["stable", true], [], []], ["a4f92ed23982", [0, 1], [[0, 0, 1, 3, ""]], "Added tag 1.0 for changeset 2ef0ac749a14", "test", "1970-01-01", ["default", true], [], []], ["2ef0ac749a14", [0, 1], [], "base", "test", "1970-01-01", ["default", false], ["1.0"], ["anotherthing"]]];
   var graph = new Graph();
   graph.scale(39);
   
@@ -1748,7 +1748,7 @@
   >>> for line in open("out"):
   ...     if line.startswith("var data ="):
   ...         print line,
-  var data = [["061dd13ba3c3", [0, 1], [[0, 0, 1, -1, ""]], "\\u80fd", "test", "1970-01-01", ["unstable", true], ["tip"], ["something"]], ["cad8025a2e87", [0, 1], [[0, 0, 1, 3, "FF0000"]], "branch commit with null character: \x00", "test", "1970-01-01", ["unstable", false], [], []], ["1d22e65f027e", [0, 1], [[0, 0, 1, 3, ""]], "branch", "test", "1970-01-01", ["stable", true], [], []], ["a4f92ed23982", [0, 1], [[0, 0, 1, 3, ""]], "Added tag 1.0 for changeset 2ef0ac749a14", "test", "1970-01-01", ["default", true], [], []], ["2ef0ac749a14", [0, 1], [], "base", "test", "1970-01-01", ["default", false], ["1.0"], ["anotherthing"]]]; (esc)
+  var data = [["061dd13ba3c3", [0, 1], [[0, 0, 1, -1, ""]], "\u80fd", "test", "1970-01-01", ["unstable", true], ["tip"], ["something"]], ["cad8025a2e87", [0, 1], [[0, 0, 1, 3, "FF0000"]], "branch commit with null character: \u0000", "test", "1970-01-01", ["unstable", false], [], []], ["1d22e65f027e", [0, 1], [[0, 0, 1, 3, ""]], "branch", "test", "1970-01-01", ["stable", true], [], []], ["a4f92ed23982", [0, 1], [[0, 0, 1, 3, ""]], "Added tag 1.0 for changeset 2ef0ac749a14", "test", "1970-01-01", ["default", true], [], []], ["2ef0ac749a14", [0, 1], [], "base", "test", "1970-01-01", ["default", false], ["1.0"], ["anotherthing"]]];
 
 capabilities