issue2551323 - Remove XHTML support

First step: raise error if xhtml used in config.ini.  Back end code is
still present to allow an admin to re-enable xhtml as a temporary
measure.

Author: rouilj

CHANGES.txt

@@ -145,6 +145,10 @@ Fixed:
 
 Features:
 
+- issue2551323 - Remove XHTML support. Disabled option to set
+  html_version to xhtml. Running roundup commands with html_version
+  set to xhtml will result in an "Invalid value for HTML_VERSION:
+  'xhtml'" error. (John Rouillard)
 - issue2551103 - add pragma 'display_protected' to roundup-admin. If
   true, print protected attributes like id, activity, actor...
   when using display or specification subcommands. (John Rouillard)

doc/upgrading.txt

@@ -112,6 +112,22 @@ values or if a value must be changed manually.
 
 This will insert the bad API login rate limiting settings.
 
+Also if you have ``html_version`` set to ``xhtml``, you will get
+an error.
+
+Use of xhtml html_version disabled (required)
+---------------------------------------------
+
+If you enabled xhtml formatted templates, you will need to
+change them to html (html4) format. Also change the value of
+``html_version`` from ``xhtml`` to ``html``.
+
+Note that the default Roundup templates use html4 so it is
+unlikely that your templates are xhtml based. See
+`issue2551323
+<https://issues.roundup-tracker.org/issue2551323>`_ for
+details on the deprecation of xhtml.
+
 Update MySQL character set/collations (required)
 ------------------------------------------------
 

roundup/configuration.py

@@ -387,6 +387,19 @@ def str2value(self, value):
             raise OptionValueError(self, value, self.class_description)
 
 
+class HtmlVersionOption(Option):
+    """Accept html4 only for now. Raise error for xhtml which is not
+       supported in roundup 2.4 and newer."""
+
+    class_description = "Allowed values: html4"
+
+    def str2value(self, value):
+        _val = value.lower()
+        if _val in ("html4"):
+            return _val
+        else:
+            raise OptionValueError(self, value, self.class_description)
+
 class EmailBodyOption(Option):
 
     """When to replace message body or strip quoting: always, never
@@ -1083,14 +1096,10 @@ def str2value(self, value):
             'or "both" (these are the three allowed values).\n'
             'The dispatcher is configured using the DISPATCHER_EMAIL\n'
             ' setting.'),
-        (Option, "html_version", "html4",
+        (HtmlVersionOption, "html_version", "html4",
             "This setting should be left at the default value of html4.\n"
-            "Support is ending for xhtml mode.\n"
-            "HTML version to generate. The templates are html4 by default.\n"
-            "If you wish to make them xhtml, then you'll need to change\n"
-            "this setting to 'xhtml' too so all auto-generated HTML\n"
-            "is compliant.\n"
-            "Allowed values: html4, xhtml"),
+            "Support for xhtml has been disabled.\n"
+            "HTML version to generate. The templates are html4 by default."),
         (TimezoneOption, "timezone", TimezoneOption.defaulttz,
             "Default timezone offset,\n"
             "applied when user's timezone is not set.",