run-tests: finish renaming of openpty fds

Author: jepler

tests/run-tests

@@ -87,15 +87,15 @@ def run_micropython(pyb, args, test_file, is_special=False):
                     def get(required=False):
                         rv = b''
                         while True:
-                            ready = select.select([primary], [], [], 0.02)
-                            if ready[0] == [primary]:
-                                rv += os.read(primary, 1024)
+                            ready = select.select([parent_fd], [], [], 0.02)
+                            if ready[0] == [parent_fd]:
+                                rv += os.read(parent_fd, 1024)
                             else:
                                 if not required or rv:
                                     return rv
 
                     def send_get(what):
-                        os.write(primary, what)
+                        os.write(parent_fd, what)
                         return get()
 
                     with open(test_file, 'rb') as f: