* lisp/net/tramp-sh.el (tramp-scp-strict-file-name-checking): New defvar.
(tramp-scp-strict-file-name-checking): New defun.
(tramp-do-copy-or-rename-file-out-of-band): Use it.
(tramp-methods) <scp, scpx>: Use "%x".
(tramp-make-copy-program-file-name): Use local quoting.
(tramp-sh-handle-make-process): Don't call
`tramp-maybe-open-connection', this happens implicitly by
`tramp-send-command'.