wxGUI: do not print messages to sys.stderr, exception is raised instead (merge from debrg6, https://trac.osgeo.org/grass/changeset/32567)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32568 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/gui_modules/gcmd.py

@@ -293,7 +293,7 @@ class Command:
     """
     def __init__ (self, cmd, stdin=None,
                   verbose=None, wait=True, rerr=False,
-                  stdout=None, stderr=sys.stderr):
+                  stdout=None, stderr=None):
 
         self.cmd = cmd
         self.stderr = stderr