mount_check doesn't work when using filesystem UUIDs instead of device names

I guess it's related to the drive.isalnum() check in swift/common/constraints.py returning false when using FS UUID instead of a block device name like sdXX

I could be wrong, but paths like /dev/sdX aren't guaranteed to be persistent with some storage configurations(1) so using UUIDs for drives would be a nice feature to have.

The workaround is either to disable mount_check in /etc/swift/*-server.conf or comment out the:

if not drive.isalnum():
    return False

in swift/common/constraints.py.

Tested using Ubuntu Precise's Swift packages:

python-swift:
  Installed: 1.4.8-0ubuntu2
  Candidate: 1.4.8-0ubuntu2
  Version table:
 *** 1.4.8-0ubuntu2 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status

(1) "4. Persistent Naming"
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/persistent_naming.html