Backtrace filtering was only disabled for exception cause, this change
ensure no backtrace filtering at all in debug mode.
* Prevent main exception filtering when debug mode is enabled;
* Test when exception cause must be displayed;
* Test how exception cause must be displayed.
Improve our filter pattern so it works for this kind of error:
SocketError: getaddrinfo: hostname nor servname provided, or not known
/usr/local/lib/ruby/2.2/timeout.rb:74:in `timeout'
/usr/local/lib/ruby/2.2/timeout.rb:125:in `timeout'
/home/tj/.gem/ruby/22/gems/net-ssh-2.9.2/lib/net/ssh.rb:207:in `new'
/home/tj/.gem/ruby/22/gems/net-ssh-2.9.2/lib/net/ssh.rb:207:in `start'
Currently the idea is to later implement a -h (or -t) option to the
command, and/or a `target' recipe keyword. Another option might be to
use the target/host key when the key/value registry will be implemented
and made available to the recipe and task DSLs.
