Remove lots of loud warnings about duplicate url names for things which don't…

Remove lots of loud warnings about duplicate url names for things which don't store state, and have the same hash.

- should make 6.002 discussion tags happier

common/lib/xmodule/xmodule/modulestore/xml.py

@@ -62,6 +62,9 @@ class ImportSystem(XMLParsingSystem, MakoDescriptorSystem):
                 """
                 # VS[compat]. Take this out once course conversion is done (perhaps leave the uniqueness check)
 
+                # tags that really need unique names--they store (or should store) state.
+                need_uniq_names = ('problem', 'sequence', 'video', 'course', 'chapter')
+
                 attr = xml_data.attrib
                 tag = xml_data.tag
                 id = lambda x: x
@@ -86,12 +89,15 @@ class ImportSystem(XMLParsingSystem, MakoDescriptorSystem):
                     orig_name = "_" + orig_name if orig_name is not None else ""
                     return tag + orig_name + "_" + hashlib.sha1(xml).hexdigest()[:12]
 
+                def looks_like_fallback(tag, url_name):
+                    """Does this look like something that came from fallback_name()?"""
+                    return url_name.startswith(tag) and re.search('[0-9a-fA-F]{12}$', url_name)
+
                 # Fallback if there was nothing we could use:
                 if url_name is None or url_name == "":
                     url_name = fallback_name()
                     # Don't log a warning--we don't need this in the log.  Do
                     # put it in the error tracker--content folks need to see it.
-                    need_uniq_names = ('problem', 'sequence', 'video', 'course', 'chapter')
 
                     if tag in need_uniq_names:
                         error_tracker("PROBLEM: no name of any kind specified for {tag}.  Student "
@@ -105,6 +111,10 @@ class ImportSystem(XMLParsingSystem, MakoDescriptorSystem):
 
                 # Make sure everything is unique
                 if url_name in self.used_names[tag]:
+                    # Always complain about modules that store state.  If it
+                    # doesn't store state, don't complain about things that are
+                    # hashed.
+                    if tag in need_uniq_names or not looks_like_fallback(tag, url_name):
                         msg = ("Non-unique url_name in xml.  This may break state tracking for content."
                                "  url_name={0}.  Content={1}".format(url_name, xml[:100]))
                         error_tracker("PROBLEM: " + msg)