CentOS 8: Fix openstack-tox-pep8 stx-integ-pylint

fix Zuul error stx-integ-pylint->
Consider explicitly re-raising using the
'from' keyword (raise-missing-from)

openstack-tox-pep8->
AttributeError: 'FlakesChecker' object has no attribute 'CONSTANT'

Change-Id: I9dd73658303e7d3906db083d3de21442e94a7d24
Signed-off-by: Yong Fu <fuyong@neusoft.com>

tools/storage-topology/storage-topology/storage_topology/exec/storage_topology.py

@@ -171,8 +171,8 @@ def convert_to_readable_size(size, orig_unit='B'):
     # convert original size to bytes
     try:
         i = units.index(orig_unit)
-    except:
+    except Exception as exc:
-        raise RuntimeError('Invalid size unit passed: %s' % (orig_unit))
+        raise RuntimeError('Invalid size unit passed: %s' % (orig_unit)) from exc
     size = size * pow(1024, i)
 
     unitIndex = int(math.floor(math.log(size, 1024)))

tox.ini

@@ -44,6 +44,11 @@ commands =
 # E402 module level import not at top of file
 # E501 line too long > 80
 # E722 do not use bare except'
+# E741 ambiguous variable name
+# F series
+# F504 '...' % ... has unused named argument(s):
+# F509 '...' % ... has unsupported format character ','
+# F841 local variable 'e' is assigned to but never used
 # H series are hacking
 # H101: Use TODO(NAME)
 # H102 is apache license
@@ -55,6 +60,7 @@ commands =
 # W291 trailing whitespace
 # W391 blank line at end of file
 # W503 line break before binary operator
+# W504 line break after binary operator
 # B series are from bugbear
 # B001 Do not use bare `except:
 # B007 Loop control variable 'cpu' not used within the loop body.
@@ -62,9 +68,10 @@ commands =
 # B010 Do not call setattr with a constant attribute value
 # F series
 # F401 'module' imported but unused
-ignore = E265,E266,E402,E501,E722
+ignore = E265,E266,E402,E501,E722,E741
+         F504,F509,F841,
          H101,H102,H104,H201,H238,H306,
-         W291,W391,W503,
+         W291,W391,W503,W504
          B001,B007,B009,B010,
          F401
 
@@ -75,7 +82,7 @@ skip_install = True
 deps =
     hacking
     flake8-bugbear<=19.3.0
-    flake8<3.6.0
+    flake8<3.8.3
 commands =
     flake8