PloneHotfix20121106: catch a ValueError exception

unescape_chr is executed with such string: "C:\Program Files\1234.jpg".
Prevent failing, and return original string in such case.

product/PloneHotfix20121106/safe_html.py

@@ -8,7 +8,10 @@ ENTITYREF_RE = re.compile(r"&(\w{1,32});?")
 
 CHR_RE = re.compile(r'\\(\d+)')
 def unescape_chr(matchobj):
-       return chr(int(matchobj.group(1), 16))
+    try:
+        return chr(int(matchobj.group(1), 16))
+    except ValueError:
+        return matchobj.group(1)
 
 
 def decode_charref(s):