has_course was incorrect, fixed

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -615,10 +615,14 @@ class MongoModuleStore(ModuleStoreWriteBase):
         otherwise, do a case sensitive search
         """
         assert(isinstance(course_key, SlashSeparatedCourseKey))
-        course_query = self._course_key_to_son(course_key)
+        location = course_key.make_usage_key('course', course_key.run)
         if ignore_case:
+            course_query = location.to_deprecated_son('_id.')
             for key in course_query.iterkeys():
-                course_query[key] = re.compile(r"(?i)^{}$".format(course_query[key]))
+                if isinstance(course_query[key], basestring):
+                    course_query[key] = re.compile(r"(?i)^{}$".format(course_query[key]))
+        else:
+            course_query = {'_id': location.to_deprecated_son()}
         return self.collection.find_one(course_query, fields={'_id': True}) is not None
 
     def has_item(self, usage_key):

common/lib/xmodule/xmodule/modulestore/xml_importer.py

@@ -15,6 +15,7 @@ from xmodule.errortracker import make_error_tracker
 from .store_utilities import rewrite_nonportable_content_links
 import xblock
 from xmodule.tabs import CourseTabList
+from xmodule.modulestore.exceptions import InvalidLocationError
 
 log = logging.getLogger(__name__)
 
@@ -165,6 +166,7 @@ def import_from_xml(
             dest_course_id = course_key
 
         if create_new_course:
+            # this tests if exactly this course (ignoring case) exists; so, it checks the run
             if store.has_course(dest_course_id, ignore_case=True):
                 log.debug(
                     "Skipping import of course with id, {0},"
@@ -172,7 +174,15 @@ def import_from_xml(
                 )
                 continue
             else:
-                store.create_course(dest_course_id.org, dest_course_id.offering)
+                try:
+                    store.create_course(dest_course_id.org, dest_course_id.offering)
+                except InvalidLocationError:
+                    # course w/ same org and course exists and store is old mongo
+                    log.debug(
+                        "Skipping import of course with id, {0},"
+                        "since it collides with an existing one".format(dest_course_id)
+                    )
+                    continue
 
         try:
             # turn off all write signalling while importing as this