oe-selftest: devtool: fix error message in _test_recipe_contents()
If a variable is being set in the recipe when we've explicitly passed
None as the value to _test_recipe_contents() indicating that it
shouldn't be set at all, then we should be printing out the variable
name in the assertion message but it seems like I forgot to do a
substitution. Also include the value for informational purposes.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
