With the merge of WT-11971, the doc-update task still failed. With a debugging patch build, it's confirmed this time the recently introduced "test/evergreen/doc_update.py" file (in WT-11885) could not be found and caused the error.

[2023/11/14 12:25:55.911] python: can't open file '/data/mci/5a8f72be949b713593899173fb10809e/wiredtiger/test/evergreen/doc_update.py': [Errno 2] No such file or directory
[2023/11/14 12:25:55.913] Command 'shell.exec' in function 'update wiredtiger docs' (step 3.2 of 5) failed: shell script encountered problem: exit code 2.  

andrew.morton@mongodb.com made a good point that the missing script only exists in the "develop" branch. A detailed check revealed the "compile wiredtiger docs" func (the one called before the failing "update wiredtiger docs" func) has the logic of checking out each of the configured doc_update_branches, which could have left a branch without the script for the following "update wiredtiger docs" func to work with (and fails).