Operations running with user in multiple groups can fail due to inability to retrieve user groups by FS

[denismo]

For example, chown only allows changing to the groups that the user belongs. If the user is in multiple groups, he can change between them. However, the fstest will fail (chown/00.t, 36) because FS can only get the number of the first group.

[denismo]

Found that the groups can be identified by reading the process record: os.system('cat /proc/%d/task/%d/status' % (pid, pid))
This prints:
...
Groups: 65532 65533 65534
...

[denismo]

from here: http://fuse.sourceforge.net/doxygen/fuse_8h.html#a04273db088e57d8242caa388193b6958, fuse_get_groups