Bug#666408: removal of disk related collection groups works

[olivier sallou]

If I remove the disk related collection_group, the gmond process works fine.

For info, I have some NFS mounted dirs.

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gpg key id: 4096R/326D8438  (keyring.debian.org)

Key fingerprint = 5FB4 6F83 D3B9 5204 6335  D26D 78DC 68DB 326D 8438