bitbake: BBHandler: Allow earlier exit for classes not found

Rather than relying on later code to error if the class isn't found,
exit earlier and more clearly from a code perspective.

(Bitbake rev: f7c55c8147329670fd5bc55b1ae3f47f25b89bab)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/parse/parse_py/BBHandler.py

@@ -56,6 +56,9 @@ def inherit(files, fn, lineno, d):
             if abs_fn:
                 file = abs_fn
 
+        if not os.path.exists(file):
+            raise ParseError("Could not inherit file %s" % (file), fn, lineno)
+
         if not file in __inherit_cache:
             logger.debug("Inheriting %s (from %s:%d)" % (file, fn, lineno))
             __inherit_cache.append( file )