Rename an internal variable and correct documentation

Nicely spotted during the PR review.

backend/entityservice/api_def/swagger.yaml

@@ -40,7 +40,7 @@ info:
     The personally identifiable information used for linking is first locally transformed
     to anonymous linking codes called [Cryptographic Longterm Keys](concepts.html#cryptographic-longterm-key)
     (CLKs). Each party then uploads its CLKs to the service for matching.
-    The service supports four different [types of outputs](concepts.html#result-types)
+    The service supports three different [types of outputs](concepts.html#result-types)
     of matching results, varying in privacy properties.
     For the CLKs to be comparable, the parties need to agree on and follow a particular
     [linkage schema](concepts.html#schema) and agree on a shared secret before generating
@@ -68,7 +68,7 @@ info:
 
     ## Matching Protocols
 
-    The Entity Service supports four different **result types** with varying privacy properties which define the produced result,
+    The Entity Service supports three different **result types** with varying privacy properties which define the produced result,
     and who may see the which part of the output.
 
     See the documentation section on [output types](./concepts.html#result-types).

backend/entityservice/tasks/permutation.py

@@ -94,13 +94,13 @@ def permute_mapping_data(project_id, run_id, len_filters1, len_filters2, parent_
         random.shuffle(remaining_new_indexes)
         log.info("Assigning random indexes for {} matched entities".format(number_in_common))
 
-        for mapping_number, group in enumerate(groups):
+        for group_number, group in enumerate(groups):
             # It should not fail because the permutation result is only available for 2 parties, but let's be to safe.
             assert 2 == len(group)
             (_, a_index), (_, b_index) = sorted(group)
 
             # Choose the index in the new mapping (randomly)
-            mapping_index = remaining_new_indexes[mapping_number]
+            mapping_index = remaining_new_indexes[group_number]
 
             a_permutation[a_index] = mapping_index
             b_permutation[b_index] = mapping_index