Merge pull request #2392 from yahonda/fix_index_hexdigest

Address `OracleEnhancedAdapter schema definition add index should raise error if too large index name cannot be shortened` failure against Oracle Database 11g

spec/active_record/connection_adapters/oracle_enhanced/schema_statements_spec.rb

@@ -333,7 +333,7 @@ class ::TestEmployee < ActiveRecord::Base; end
           ("index_test_employees_on_first_name_and_middle_name_and_last_name"))
       else
         expect(@conn.index_name("test_employees", column: ["first_name", "middle_name", "last_name"])).to eq(
-          "i" + OpenSSL::Digest::SHA1.hexdigest("idx_on_first_name_middle_name_last_name_ee1d3958bc")[0, 29]
+          "i" + OpenSSL::Digest::SHA1.hexdigest("index_test_employees_on_first_name_and_middle_name_and_last_name")[0, 29]
         )
       end
     end