Before this change, the default SFTP encoding (`Slash,Del,Ctl,Dot`, the same
as rclone's standard form) passed names through unchanged, so a name on the
server containing a control character, such as a raw newline, reached rclone
in a non-standard form. Other backends, such as local on Linux, list the same
name in the standard form (`␊`), so the two never matched: syncing such a file
from SFTP to local deleted it on every second run, and bisync recorded
listings that didn't match the files.
After this change, the default encoding is `Slash,Dot`, the same as the local
backend's default on Linux, so control characters in names on the server are
converted to and from the standard form. Servers running on Windows can add the
Windows restricted characters with `--sftp-encoding`, as now documented.
The issue was discovered on the bisync integration tests.
This also fixes `mkParentDir`, which encoded the parent `.` of a top-level
file as a name. With the new default encoding, that created a stray `．`
directory on the server.
nielash
0c9826d344