Prevent appending schema name to function-based index calls

Question

When a function-based index created using

CREATE INDEX I_FN_TEST
ON T_TEST (TESTPKG.TESTFUNC (TEST_COLUMN));

Oracle appends the current schema name to the TESTPKG call, making it CURRSCHEMA.TESTPKG.TESTFUNC. This is observed running by

SELECT column_expression
  FROM dba_ind_expressions
 WHERE index_owner = 'CURRSCHEMA' AND index_name = 'I_FN_TEST';

COLUMN_EXPRESSION                                 
--------------------------------------------------
"CURRSCHEMA"."TESTPKG"."TESTFUNC"("TEST_COLUMN")         
1 row selected.

CURRSCHEMA is my dev schema and DDL diffs are regularly created to ship developments to production with DBMS_METADATA.GET_DDL.

The problem is now our diff DDL's contains a schema name that does (and should) not exists at the target. Is there any way to prevent appending current schema name to index definition?