Fix: OperationFailure when changing keys on existing index

Closes #1180

CHANGES.rst

@@ -21,12 +21,13 @@ New
 
 Fixed
 ~~~~~
-- v0.8: ``OperationFailure`` performing MongoDB full text searches (`#1176`_)
-- ``AttributeError`` on Python 2.7 when obsolete ``JSON`` or ``XML`` settings are used (`#1175`_).
-- ``TypeError argument of type 'NoneType' is not iterable`` error when using document embedding in conjuction with soft deletes (`#1120`_)
+- ``mongo_indexes``: "OperationFailure" when changing the keys of an existing index (`#1180`_)
+- v0.8: "OperationFailure" performing MongoDB full text searches (`#1176`_)
+- "AttributeError" on Python 2.7 when obsolete ``JSON`` or ``XML`` settings are used (`#1175`_).
+- "TypeError argument of type 'NoneType' is not iterable" error when using document embedding in conjuction with soft deletes (`#1120`_)
 - ``allow_unknown`` validation rule fails with nested dict fields (`#1163`_)
 - Updating a field with a nullable data relation fails when value is null (`#1159`_)
-- ``cerberus.schema.SchemaError`` when ``VALIDATE_FILTERS = True``. (`#1154`_)
+- "cerberus.schema.SchemaError" when ``VALIDATE_FILTERS = True``. (`#1154`_)
 - Serializers fails when array of types is in schema. (`#1112`_)
 - Replace the broken ``make audit`` shortcut with ``make check``, add the
   command to ``CONTRIBUTING.rst`` it was missing.  (`#1144`_)
@@ -54,6 +55,7 @@ Docs
 - Improve changelog format to reduce noise and increase readability. (`#1143`_)
 
 .. _`#1181`: https://github.com/pyeve/eve/issues/1181
+.. _`#1180`: https://github.com/pyeve/eve/issues/1180
 .. _`#1176`: https://github.com/pyeve/eve/issues/1176
 .. _`#1175`: https://github.com/pyeve/eve/issues/1175
 .. _`#1173`: https://github.com/pyeve/eve/issues/1173

eve/io/mongo/mongo.py

@@ -1027,6 +1027,9 @@ def _create_index(app, resource, name, list_of_keys, index_options):
     For example:
         {"sparse": True}
 
+    .. versionchanged:: 0.8.1
+       Add support for IndexKeySpecsConflict error. See #1180.
+
     .. versionadded:: 0.6
 
     """
@@ -1056,11 +1059,9 @@ def _create_index(app, resource, name, list_of_keys, index_options):
         try:
             coll.create_index(list_of_keys, **kw)
         except pymongo.errors.OperationFailure as e:
-            if e.code == 85:
-                # This error is raised when the definition of the index has
-                # been changed, we didn't find any spec out there but we
-                # think that this error is not going to change and we can
-                # trust.
+            if e.code in (85, 86):
+                # raised when the definition of the index has been changed.
+                # (https://github.com/mongodb/mongo/blob/master/src/mongo/base/error_codes.err#L87)
 
                 # by default, drop the old index with old configuration and
                 # create the index again with the new configuration.