Enable the ruff rules that already report nothing

Every rule added here is at zero once the previous commit lands, so it costs
no cleanup: the point is that a future patch cannot introduce one without the
ruff job failing. They are the rest of pyflakes' format-string checks,
flake8-2020, most of bugbear, the pylint warnings that describe bugs rather
than style, four flake8-async rules for blocking calls in coroutines, and
some RUF, LOG, PGH, PIE, ISC and EXE rules in the same spirit. Each was
confirmed to fire on a synthetic violation, so none is silently inert under
the py37 target.

Rules are named by group wherever the group is already clean, and each prefix
stops short of a rule that is not: PLW150 rather than PLW15, which would pull
in PLW1510. Bugbear is listed rule by rule apart from B02 and B03, since
B006, B007 and B018 are all left out on purpose.

ruff.toml

@@ -53,32 +53,68 @@ quote-style = "preserve"
 [lint]
 select = [
     "E9",       # unparseable file
-    "F63",      # `is` against a literal, assert on a tuple, bad print/if-tuple
-    "F7",       # statements in impossible positions: return/yield outside a
-                # function, break/continue outside a loop, except clause not last
+    "F4",       # imports: unused, shadowed by a loop, star import or a name from one, __future__ misuse
+    "F5",       # %-format and str.format checked against their arguments: bad conversions, wrong counts
+    "F6",       # duplicate dict and set keys, bad starred assignment, `is` against a literal, assert on a tuple
+    "F7",       # return outside a function, break outside a loop, an except clause that is not last
     "F81",      # redefinition of an unused name (shadowed def/class)
     "F82",      # undefined name, undefined name in __all__, use before assignment
-    "F401",     # unused import
-    "F402",     # import shadowed by a loop variable
     "F541",     # f-string with no placeholders
+    "F842",     # local that is annotated but never assigned
+    "F901",     # `raise NotImplemented`, which raises TypeError rather than NotImplementedError
+    "YTT",      # version checks that break on 3.10 and later, such as sys.version[2] or version_info[1] < 7
     "E401",     # several imports on one line
     "E701",     # several statements on one line
-    "E711",     # comparison to None with == rather than is
-    "E712",     # comparison to True/False with == rather than truthiness
-    "E713",     # `not x in y` rather than `x not in y`
+    "E71",      # == against None or True/False, and `not x in y` / `not x is y` written the long way round
     "PLC0414",  # import alias that renames nothing
     "PLE",      # pylint errors: bad string format, invalid returns, ...
+    "PLR0124",  # a value compared with itself
+    "PLR1722",  # exit() or quit(), which only exist when site.py has run
+    "PLW01",    # self-assignment, assert on a literal, unraised exception, NaN compare, else on a breakless loop
+    "PLW0211",  # staticmethod whose first argument is named self or cls
+    "PLW0245",  # super called without brackets, which yields the class
+    "PLW0406",  # a module importing itself
+    "PLW0642",  # assignment to self or cls
+    "PLW0711",  # `except A + B`, which catches whatever the addition returns
+    "PLW150",   # bad open() mode, copy.copy(os.environ), non-string os.environ.get default, Popen preexec_fn
+    "PLW2101",  # `with lock:` on a lock created in place, which locks nothing
     "T100",     # forgotten pdb/breakpoint call
-    "W6",       # invalid escape sequence in a non-raw string, and any future
-                # deprecated-construct warning pycodestyle adds
+    "W6",       # invalid escape sequence in a non-raw string, and future deprecated-construct warnings
+    "B002",     # `++x`, which is two unary plus signs, not an increment
+    "B003",     # assignment to os.environ, which never reaches the environment
+    "B004",     # hasattr(x, '__call__') rather than callable(x)
+    "B005",     # .strip() with several characters, which strips a set of them
+    "B008",     # function call in a default argument, evaluated once at import
+    "B011",     # `assert False`, which disappears under python -O
+    "B012",     # break/continue/return in a finally, silently discarding the exception
+    "B013",     # single-element tuple in an except clause
+    "B014",     # the same exception listed twice in one except clause
     "B015",     # comparison whose result is discarded
-    "B020",     # loop control variable overrides the iterable it iterates
-    "B023",     # closure captures a loop variable, so every closure sees the
-                # last value rather than the one from its iteration
-    "B035",     # dict comprehension with a static key
-    "RUF006",   # asyncio.create_task result discarded.  The loop keeps only a
-                # weak reference, so an unreferenced task can be collected
-                # while it is still pending, and the work is silently dropped
+    "B016",     # raising something that is not an exception
+    "B017",     # assertRaises(Exception), which passes on the wrong error
+    "B019",     # lru_cache on a method, which keeps every instance alive
+    "B02",      # all of B02x: loop variable overriding its iterable, closure over a loop variable
+    "B03",      # all of B03x: non-exception except, groupby reuse, `x: y` for `x = y`, dup set item
+    "ASYNC210", # blocking HTTP call (requests, urllib) inside a coroutine
+    "ASYNC222", # blocking wait on a child process inside a coroutine
+    "ASYNC250", # input() inside a coroutine
+    "ASYNC251", # time.sleep() inside a coroutine
+    "RUF006",   # asyncio.create_task result discarded, so the task can be collected while still pending
+    "RUF016",   # subscript with a type that cannot index the container
+    "RUF017",   # sum() over lists, which is quadratic in the result length
+    "RUF018",   # assignment inside an assert, so the side effect disappears under python -O
+    "RUF024",   # dict.fromkeys with a mutable value, shared by every key
+    "RUF034",   # if-else whose two branches are the same expression
+    "RUF060",   # membership test against a collection that is always empty
+    "RUF100",   # noqa that suppresses nothing
+    "ISC001",   # implicitly concatenated strings on one line, usually a comma missing from a list
+    "LOG",      # logging misuse: hand-built Logger, exception() outside a handler, logging.warn, root logger
+    "PGH",      # blanket `# noqa` and `# type: ignore`, and assertions on mock attributes that always pass
+    "PIE794",   # a class field defined twice, so the first is dead
+    "PIE796",   # enum with duplicate values, which silently aliases members
+    "EXE003",   # shebang that does not name python
+    "EXE004",   # whitespace before the shebang, which stops it working
+    "EXE005",   # shebang after the first line, where it does nothing
 ]
 
 # Deliberately not selected, though currently at zero: B905 (zip without an