Prebuild cache not working on some hosts

Hi all,

Not really expecting an answer from Swift but the following might still help.

Issue:
Prebuild cache is not working.

Cause:
Prebuild cache is run using a fixed user agent string: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Firefox/52.0

Host mijndomein.nl is quite popular in the Netherlands.
This host rejects this user agent with an 403 response, “Your client or browser version is being used to send malformed or invalid requests.
Please update your browser if possible.”
Alas, Swift Performance Lite does not give any feedback on this issue, not in normal and not in debug mode; it just runs prebuild without anything being prebuilt and without any notices.

Suggested improvements:
– make the user agent string in performance.php filterable so it’s easy to change it
– extend logging info from performance.php beyond 5xx responses & redirects.

Besides above: Swift Performance Lite has been my go to performance plugin since long time and I want to thank you for that!