Filebackend reports error when trying to rename file due to concurrent processes
Due to concurrent processes it happens that a temp-cache-file gets renamed while an other process is just writing it.
Further there is an error in the error handling.
- added an exclusive lock for the writing operation
- added counters for a break to avoid an endless loop due to file system errors
- added timers for getting the process to sleep
- fixed error handling
As this is the same in FLOW3 I also reported the bug and fixes there.
Please find TYPO3 specific fixes attached.