ZF-10511: Add a log call with level DEBUG on cache save()
Add a log call with level DEBUG on cache save().
For debugging this would be really helpful. Example: we had some serious caching issues, because our frontend did cache save() calls, which it shouldn't. But there was no way of noticing it, so I added a log() call on save, and it was really easy to spot the problems.
Of course the log level should be low enough to not show up always.