If a request fails with "x509: certificate signed by unknown authority",
the B2 backend now returns the error without retrying the request.
Closes#3556Closes#2355
Return valid directory info from Lstat() for parent directories of the
specified filename. Previously only "/" and "." were valid directories.
Also set directory mode as this is checked by archiver.
Closes#2063
The default value of the `--host` flag was set to 'H' (the shorthand
version of the flag), this caused the snapshot lookup to fail.
Also add shorthand `-H` for `backup` command.
Closes#2040