Maintenance plans fail when the network path for the mirror backup is not found. (4220696)

Description:   Maintenance plans fail when the network path for the mirror backup is not found. The customer is concerned that if the network share should be offline then his maintenance plans will fail to produce a backup..

Steps To Reproduce:
1. Create maintenance plan which creates both a full backup and a mirror backup and verbose logging.
2. THe full backup should be placed on a local drive, the mirror to this network location \\vincent\vincent...(please note that this location does not exist)
3. Run the MP
4. Note no backup is created.
5. Review verbose logs and note error that network path could not be found which "failed" the MP.