Show caching message when verbose = 4?

[kendonB]

I have a job that might be I/O heavy due to caching and I can't quite tell as when I look at the txtq or batchtools logs the most I can see is target ..., loading, and unloading.

The storring stage naturally fits with verbose = 4, I think.

something like : storring <target_name> printed like the other messages would do it. Could also consider chucking all the messages into the worker txtq's as well.

[wlandau]

Sounds reasonable and easy to implement. I am hoping to get to this and #539 later this week.