Remove unnecessary hacking from test reqs

It is used in only pep8 target which does not actually use
the requirements files.

Also remove the outdated note about pip's dependency resolver and adds
the note about lower bounds (which are no longer tested).

Change-Id: I213ec4f4132332d756ea147f42bb46413ef918a4
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

requirements.txt

@@ -1,6 +1,6 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
+# Requirements lower bounds listed here are our best effort to keep them up to
+# date but we do not test them so no guarantee of having them all correct. If
+# you find any incorrect lower bounds, let us know or propose a fix.
 
 openstacksdk>=0.13.0 # Apache-2.0
 osc-lib>=1.8.0 # Apache-2.0

test-requirements.txt

@@ -1,9 +1,3 @@
-# The order of packages is significant, because pip processes them in the order
-# of appearance. Changing the order has an impact on the overall integration
-# process, which may cause wedges in the gate later.
-
-hacking>=3.0.1,<3.1.0 # Apache-2.0
-
 coverage!=4.4,>=4.0 # Apache-2.0
 ddt>=1.0.1 # MIT
 python-subunit>=1.0.0 # Apache-2.0/BSD

tox.ini

@@ -27,7 +27,7 @@ commands =
 skip_install = True
 deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
-  hacking
+  hacking>=7.0.0,<7.1.0
 commands =
   flake8 {posargs}