avocado.core.multiplexer: Apply filters to whole tree

Currently only tree produced from yaml file is filtered. This patch
changes the logic to first produce the full tree and then apply filters.
The difference is that this way one can filter also nodes defined via
`avocado_devault_params` like avocado-vt params or `--mux-inject` ones.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/multiplexer.py

@@ -389,11 +389,12 @@ class Mux(object):
         filter_only = getattr(args, 'filter_only', None)
         filter_out = getattr(args, 'filter_out', None)
         if mux_files:
-            mux_tree = yaml2tree(mux_files, filter_only, filter_out)
+            mux_tree = yaml2tree(mux_files)
         else:   # no variants
             mux_tree = tree.TreeNode()
         if getattr(args, 'default_avocado_params', None):
             mux_tree.merge(args.default_avocado_params)
+        mux_tree = tree.apply_filters(mux_tree, filter_only, filter_out)
         self.variants = MuxTree(mux_tree)
         self._mux_path = getattr(args, 'mux_path', None)
         if self._mux_path is None: