bitbake: Fix default function parameter assignment to a list

With python you should not assign a list as the default value of a
function parameter - because a list is mutable, the result will be that
the first time a value is passed it will actually modify the default.
Reference:

http://docs.python-guide.org/en/latest/writing/gotchas/#mutable-default-arguments

(Bitbake rev: 7859f7388f2e3f675d0e1527cfde18625f36f637)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/msg.py

@@ -150,7 +150,7 @@ loggerDefaultVerbose = False
 loggerVerboseLogs = False
 loggerDefaultDomains = []
 
-def init_msgconfig(verbose, debug, debug_domains = []):
+def init_msgconfig(verbose, debug, debug_domains=None):
     """
     Set default verbosity and debug levels config the logger
     """
@@ -158,7 +158,10 @@ def init_msgconfig(verbose, debug, debug_domains = []):
     bb.msg.loggerDefaultVerbose = verbose
     if verbose:
         bb.msg.loggerVerboseLogs = True
-    bb.msg.loggerDefaultDomains = debug_domains
+    if debug_domains:
+        bb.msg.loggerDefaultDomains = debug_domains
+    else:
+        bb.msg.loggerDefaultDomains = []
 
 def constructLogOptions():
     debug = loggerDefaultDebugLevel