[FIX] tools: do not crash on wrong translations in view

During the construction a xml/html_translate content, in case of a wrongly
translated part (e.g. not correctly escaped char or bad xml tag), escape the
translation.

The verification is done during the rendering on the view which is not the most
optimal solution but has the advantage of working on system with some broken
translations and does not requires to reload the translations.

In master version, the verification could be done when loading the .po files.

openerp/tools/translate.py

@@ -169,9 +169,10 @@ class XMLTranslator(object):
             </div>
 
     """
-    def __init__(self, callback, method):
+    def __init__(self, callback, method, parser=None):
         self.callback = callback        # callback function to translate terms
         self.method = method            # serialization method ('xml' or 'html')
+        self.parser = parser            # parser for validating translations
         self._done = []                 # translated strings
         self._todo = []                 # todo strings that come after _done
         self.needs_trans = False        # whether todo needs translation
@@ -208,7 +209,15 @@ class XMLTranslator(object):
         """ Translate text.strip(), but keep the surrounding spaces from text. """
         term = text.strip()
         trans = term and self.callback(term)
-        return text.replace(term, trans) if trans else text
+        if trans:
+            try:
+                # parse the translation to validate it
+                etree.fromstring("<div>%s</div>" % encode(trans), parser=self.parser)
+            except etree.ParseError:
+                # fallback: escape the translation
+                trans = escape(trans)
+            text = text.replace(term, trans)
+        return text
 
     def process(self, node):
         """ Process the given xml `node`: collect `todo` and `done` items. """
@@ -284,9 +293,10 @@ def html_translate(callback, value):
     if not value:
         return value
 
-    trans = XMLTranslator(callback, 'html')
+    parser = etree.HTMLParser(encoding='utf-8')
+    trans = XMLTranslator(callback, 'html', parser)
     wrapped = "<div>%s</div>" % encode(value)
-    root = etree.fromstring(wrapped, etree.HTMLParser(encoding='utf-8'))
+    root = etree.fromstring(wrapped, parser)
     trans.process(root[0][0])               # html > body > div
     return trans.get_done()[5:-6]           # remove tags <div> and </div>