v2:
- Moved the btrfs available test into the subclause where it is used.
Note I got tired of fighting emacs indentation mode and I pushed a
whitespace only patch which fixes the indentation to be 4 spaces
instead of 2 spaces:
https://github.com/libguestfs/libguestfs/commit/df54c75d4c53ed580e5269306...
This v2 patch requires that one.
Rich.