RFC: Shouldn't '-D' (i.e. 'set -x') also apply for usr/sbin/rear ?

[jsmeix]

During
#1241
I noticed that for "rear -D ..."
there is no 'set -x' output in the log file
which makes it nedlessly hard to debug
issues in usr/sbin/rear itself.

Therefore I like to suggest that for '-D'
the 'set -x' is also done in usr/sbin/rear itself.

Or is there a good reason why for '-D'
no 'set -x' is done in usr/sbin/rear itself?