chimera: prevent attempts to remove '.' and '..'

we have in place checks for NFS, but not for the
other protocols.

Acked-by: Paul MIllar
Target: master, 2.11 ..  2.6
Require-book: no
Require-notes: no
(cherry picked from commit 8685d9a44881004f276c3f11bbe764c2f53953e8)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Merge pull request #1009 from kofemann/fix-chimera-rm-2.10

chimera: prevent attempts to remove '.' and '..'