cleanup flake8 checks

- make code style exceptions tailored to specific files, so that it's less likely that new violations creep into the code.

setup.cfg

@@ -4,13 +4,92 @@ markers =
     allow_cache_wipe
 
 [flake8]
+# for reference ...
+#   E121 continuation line under-indented for hanging indent
+#   E122 continuation line missing indentation or outdented
+#   E123 closing bracket does not match indentation of opening bracket's line
+#   E125 continuation line with same indent as next logical line
+#   E126 continuation line over-indented for hanging indent
+#   E127 continuation line over-indented for visual indent
+#   E128 continuation line under-indented for visual indent
+#   E221 multiple spaces before operator
+#   E226 missing whitespace around arithmetic operator
+#   E261 at least two spaces before inline comment
+#   E265 block comment should start with '# '
+#   E301 expected 1 blank line
+#   E305 expected 2 blank lines after class or function definition
+#   E401 multiple imports on one line
+#   E402 module level import not at top
+#   E501 line too long
+#   E722 do not use bare except
+#   E731 do not assign a lambda expression, use def
+#   E741 ambiguous variable name
+#   F401 import unsused
+#   F403 from ... import * used, unable to detect undefined names
+#   F405 undefined or defined from star imports
+#   F811 redef of unused var
+#   F821 undefined name
+#   W391 blank line at end of file
+#   #### Pick either W503, or W504 - latest recommendation from pep8 is to ignore W503
+#   W503 line break before binary operator
+#   W504 line break after binary operator
+
+# borg code style guidelines:
+ignore = E226, W503
+
+# Code style violation exceptions:
 # please note that the values are adjusted so that they do not cause failures
 # with existing code. if you want to change them, you should first fix all
 # flake8 failures that appear with your change.
-ignore = E122,E123,E125,E126,E127,E128,E226,E402,E722,E731,E741,
-         F401,F405,F811,
-         W504
-# line length long term target: 120
-max-line-length = 255
-exclude = build,dist,.git,.idea,.cache,.tox,docs/conf.py
+per_file_ignores =
+    conftest.py:E402,E501,F401
+    docs/conf.py:E121,E126,E265,E305,E401,E402
+    scripts/errorlist.py:F401
+    src/borg/archive.py:E122,E125,E127,E402,E501,F401,F405,W504
+    src/borg/archiver.py:E126,E127,E128,E501,E722,E731,E741,F401,F405,W504
+    src/borg/cache.py:E127,E128,E402,E501,E722,W504
+    src/borg/fuse.py:E402,E501,E722,W504
+    src/borg/fuse_impl.py:F811
+    src/borg/locking.py:E128,E501,E722
+    src/borg/remote.py:E128,E501,F405
+    src/borg/repository.py:E126,E128,E501,F401,F405,W504
+    src/borg/shellpattern.py:E501
+    src/borg/upgrader.py:E501
+    src/borg/xattr.py:E402
+    src/borg/crypto/key.py:E125,E128,E402,E501,F401,F405,W504
+    src/borg/crypto/keymanager.py:E126,E128,E501,F401
+    src/borg/crypto/nonces.py:E128,E501
+    src/borg/helpers/__init__.py:F401,F405
+    src/borg/helpers/checks.py:F401
+    src/borg/helpers/errors.py:F405
+    src/borg/helpers/fs.py:F405
+    src/borg/helpers/manifest.py:E128,E402,E501,F405
+    src/borg/helpers/misc.py:E402,E722,F401,F405
+    src/borg/helpers/msgpack.py:E127,F405
+    src/borg/helpers/parseformat.py:E402,E501,E741,F401,F405
+    src/borg/helpers/process.py:E402,F401,W504
+    src/borg/helpers/progress.py:E402
+    src/borg/platform/__init__.py:F401,F811
+    src/borg/platform/base.py:E402
+    src/borg/testsuite/__init__.py:E501,F401
+    src/borg/testsuite/archive.py:E128,W504
+    src/borg/testsuite/archiver.py:E128,E501,E722,F401,F405,F811
+    src/borg/testsuite/benchmark.py:F401,F811
+    src/borg/testsuite/chunker.py:E501,F405
+    src/borg/testsuite/chunker_pytest.py:F401
+    src/borg/testsuite/chunker_slow.py:F405
+    src/borg/testsuite/crypto.py:E126,E501,E741
+    src/borg/testsuite/file_integrity.py:F401
+    src/borg/testsuite/hashindex.py:F401
+    src/borg/testsuite/helpers.py:E126,E127,E128,E501,F401
+    src/borg/testsuite/key.py:E501,F401
+    src/borg/testsuite/locking.py:E126,E128,E501,E722,F401
+    src/borg/testsuite/patterns.py:E123
+    src/borg/testsuite/platform.py:E128,E501,F401,F811
+    src/borg/testsuite/repository.py:E128,E501,F401
+    src/borg/testsuite/shellpattern.py:E123
+    src/borg/testsuite/upgrader.py:F405
+
+max_line_length = 120
+exclude = build,dist,.git,.idea,.cache,.tox