[TASK] Cache file backend shows invalid identifier with exception
[TASK] Cache file backend shows invalid identifier with exception

This makes it (a little) easier to debug those exceptions.

Change-Id: I58d68aebce6e7de3cc8ff55dbef5bdf461201627
Original-Commit-Hash: 9e5715e5c6f680ad4a81859f21d413943be0653c

daniellienert/flow-development-collection,fcool/flow-development-collection,albe/flow-development-collection,fcool/flow-development-collection,dlubitz/flow-development-collection,robertlemke/flow-development-collection,neos/flow-development-collection,chewbakartik/flow-development-collection,dfeyer/flow-development-collection,bwaidelich/flow-development-collection,kdambekalns/flow-development-collection,gerhard-boden/flow-development-collection,robertlemke/flow-development-collection,neos/flow-development-collection,gerhard-boden/flow-development-collection,mkeitsch/flow-development-collection,dfeyer/flow-development-collection,bwaidelich/flow-development-collection,robertlemke/flow-development-collection,robertlemke/flow-development-collection,bwaidelich/flow-development-collection,aertmann/flow-development-collection,daniellienert/flow-development-collection,dfeyer/flow-development-collection,kitsunet/flow-development-collection,fcool/flow-development-collection,mkeitsch/flow-development-collection,dlubitz/flow-development-collection,chewbakartik/flow-development-collection,kitsunet/flow-development-collection,albe/flow-development-collection,fcool/flow-development-collection,mkeitsch/flow-development-collection,kdambekalns/flow-development-collection,chewbakartik/flow-development-collection,neos/flow-development-collection,dlubitz/flow-development-collection,aertmann/flow-development-collection,aertmann/flow-development-collection,daniellienert/flow-development-collection,neos/flow-development-collection,kitsunet/flow-development-collection,dfeyer/flow-development-collection,kdambekalns/flow-development-collection,albe/flow-development-collection,gerhard-boden/flow-development-collection,kdambekalns/flow-development-collection