Restore qiskit/util.py

The qiskit/util.py will need to be deprecated a bit longer it's still in
active use by downstream packages and it was right on the boundary of
being deprecated long enough anyway so being a bit more conservative on
this is probably for the best anyway.

qiskit/util.py

@@ -0,0 +1,29 @@
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Common utilities for Qiskit."""
+
+# Deprecated: for backwards compatibility to be removed in a future release
+from qiskit.utils.deprecation import deprecate_arguments
+from qiskit.utils.deprecation import deprecate_function
+from qiskit.utils.multiprocessing import is_main_process
+from qiskit.utils.multiprocessing import local_hardware_info
+from qiskit.utils.units import apply_prefix
+
+
+__all__ = [
+    "deprecate_arguments",
+    "deprecate_function",
+    "is_main_process",
+    "local_hardware_info",
+    "apply_prefix",
+]

releasenotes/notes/deprecation-cleanup-3d3e203e2d6e6f31.yaml

@@ -1,8 +1,5 @@
 ---
 upgrade:
-  - |
-    The ``qiskit.util`` module has been removed. It was originally deprecated
-    in the 0.17 release
   - |
     The ``DAGCircuit.extend_back()`` method has been removed. It was originally
     deprecated in the 0.13.0 release. Instead you can use the