How to find out which patch caused issue whie applying a merged patch

To minimize downtime, Apps patches are usually merged and applied. Sometimes, a worker may fail while applying the merged patch. Oracle will usually ask you which patch failed, if you log an SR with them for the issue. Here's how I singled out the patches in a merged patch containing 224 patches:

Worker failed with this error:

sqlplus -s APPS/*****
@$PON_TOP/patch/115/sql/ponTemplateUpg.sql
declare
*
ERROR at line 1:
ORA-01001: invalid cursor
ORA-06512: at "APPS.FND_ATTACHED_DOCUMENTS2_PKG", line 899
ORA-01400: cannot insert NULL into ("APPLSYS"."FND_LOBS"."FILE_CONTENT_TYPE")
ORA-06512: at line 284

cd to directory which has the unzipped source patches

$ find . -name u*.drv -print -exec egrep ponTemplateUpg.sql {} \;

./4028294/u4028294.drv
copy pon patch/115/sql ponTemplateUpg.sql 115.3.11510.4
# file-version-parsed pon patch/115/sql ponTemplateUpg.sql 115.3.11510.4
sql pon patch/115/sql ponTemplateUpg.sql none none none sqlplus &phase=upg

./5150810/u5150810.drv
copy pon patch/115/sql ponTemplateUpg.sql 115.3.11510.4
# file-version-parsed pon patch/115/sql ponTemplateUpg.sql 115.3.11510.4
sql pon patch/115/sql ponTemplateUpg.sql none none none sqlplus &phase=upg checkfile:pon:patch/115/sql:ponTemplateUpg.sql

$ adident Header $PON_TOP/patch/115/sql/ponTemplateUpg.sql
$PON_TOP/patch/115/sql/ponTemplateUpg.sql:
$Header ponTemplateUpg.sql 115.3.11510.4 2004/11/02 09:18:50 ssthakur ship $

$ adident Header ./4028294/pon/patch/115/sql/ponTemplateUpg.sql
./4028294/pon/patch/115/sql/ponTemplateUpg.sql:
$Header ponTemplateUpg.sql 115.3.11510.4 2004/11/02 09:18:50 ssthakur ship $

$ adident Header ./5150810/pon/patch/115/sql/ponTemplateUpg.sql
./5150810/pon/patch/115/sql/ponTemplateUpg.sql:
$Header ponTemplateUpg.sql 115.3.11510.4 2004/11/02 09:18:50 ssthakur ship $

Both the patches 4028294 and 5150810 contain the same version of ponTemplateUpg.sql. So this error can occur due to any of these two patches.