Providing a custom_schema results in 2x validation

[braingram]

asdf/asdf/_asdf.py

Lines 583 to 592 in 9d7ff2e

	def _validate(self, tree, custom=True, reading=False):
	with self._blocks.options_context():
	# If we're validating on read then the tree
	# is already guaranteed to be in tagged form.
	tagged_tree = tree if reading else yamlutil.custom_tree_to_tagged_tree(tree, self)
	schema.validate(tagged_tree, self, reading=reading)
	# Perform secondary validation pass if requested
	if custom and self._custom_schema:
	schema.validate(tagged_tree, self, self._custom_schema, reading=reading)

Investigate what would be required to consolidate these 2 calls to validate into 1.