Prior to this commit, the ssh communicator would use the default cipher
list in Net::SSH to negociate which ciphers it should use between hosts.
Due to a bug in Net::SSH and the position of the `none` cipher in its
default cipher list, if a host supported the none cipher, but also
only supported other ciphers that came after none in the default list,
it would accept none and attempt to use that cipher instead of the other
supported ciphers. This commit fixes that behavior by copying the
default cipher list from Net::SSH and placing none last in the list so
that other ciphers can be used in the negotiation before attempting to
use the unsecure none cipher.
Prevent sending empty data strings to defined blocks handling
stderr and stdout output. These can occur when the garbage
marker is identified and collected data pruned, but no remaining
data is left to send.
Fixes#8259
Brian Cain
Chris Roberts