* test/lisp/net/tramp-tests.el (tar-mode): Require.
(tramp-test10-write-region-other-file-name-handler): New test.
(tramp-test31-interrupt-process, tramp-test31-signal-process):
Tag them :unstable unconditionally.
* test/lisp/net/tramp-resources/foo.tar.gz: New resource file.
