The CP4 autofill did not run this morning from crontab because I had checked its pending changes into SVN earlier and it became a non-executable file. The file was originally non-executable when it was first committed to the repository. I subsequently made it executable so I could call it directly and not as an argument to python. Inadvertently I did this incorrectly by just changing the working-directory file's permissions (chmod 775 cp4_fill.py).

I should have made it executable with the svn command:

svn propset svn:executable on cp4_fill.py

this command makes the local file executable, and changes the file's metadata ready for a commit to the repository.

By the way, normally a commit like I did this morning will not change the file permissions, but in this case the file has the $Header$ keyword substitution enabled, so when committed both the file's contents and its permissions were "corrected".