fixing unique index on Oracle

modules/activiti-engine/src/main/resources/org/activiti/db/create/activiti.oracle.create.sql

@@ -188,10 +188,6 @@ alter table ACT_RU_EXECUTION
     foreign key (SUPER_EXEC_) 
     references ACT_RU_EXECUTION (ID_);
     
-alter table ACT_RU_EXECUTION
-    add constraint UNIQ_RU_BUS_KEY
-    UNIQUE (PROC_DEF_ID_, BUSINESS_KEY_);
-    
 alter table ACT_ID_MEMBERSHIP 
     add constraint FK_MEMB_GROUP 
     foreign key (GROUP_ID_) 
@@ -255,4 +251,4 @@ create unique index business_key_ru_idx on ACT_RU_EXECUTION
 -- see http://stackoverflow.com/questions/675398/how-can-i-constrain-multiple-columns-to-prevent-duplicates-but-ignore-null-value
 create unique index business_key_hi_idx on ACT_HI_PROC_INST
    (case when BUSINESS_KEY_ is null then null else PROC_DEF_ID_ end,
-    case when BUSINESS_KEY_ is null then null else BUSINESS_KEY_ end);
\ No newline at end of file
+    case when BUSINESS_KEY_ is null then null else BUSINESS_KEY_ end);