All wic exceptions are now inherited from new base exception
class WicError. It makes them easy to maintain and catch.
Processing of exceptions is done this way:
Known wic exceptions cause wic to print error message to stdout.
Unknown exceptions are not catched anymore and produce standard
python traceback.
(From OE-Core rev: e5e2c18ce4344c14d9e52ece916333bd0a619281)
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>