rconfig fails with ORA-25152: TEMPFILE cannot be dropped at this time

Was doing a single instance db to RAC conversion on a 11.2.0.3 cluster using rconfig and the process fails with ORA-25152 during "Setting TEMP tablespace" step.
Verified if the temp segments are in use but no processes are accessing.
The fix that finally worked is 

• drop the tempfile using 'alter database tempfile 'xxx/temp01.dbf' drop including datafiles;
• run rconfig and it worked fine this time
• add tempfile back using 'alter tablespace temp add tempfile size 4000M;

Did notice a few bug reports on Metalink however there's no workaround available so the above should do the trick if you happen run into this issue.