Harden `sig_prog()` retries, adjust debugger test timeouts

Retry signal delivery in `sig_prog()` up to `tries`
times (default 3) w/ `canc_timeout` sleep between
attempts; only fall back to `_KILL_SIGNAL` after all
retries exhaust. Bump default timeout 0.1 -> 0.2.

Also,
- `test_multi_nested_subactors_error_through_nurseries`
  gives the first prompt iteration a 5s timeout even
  on linux bc the initial crash sequence can be slow
  to arrive at a `pdb` prompt

(this commit msg was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

tests/conftest.py

@@ -199,15 +199,40 @@ def ci_env() -> bool:
 def sig_prog(
     proc: subprocess.Popen,
     sig: int,
-    canc_timeout: float = 0.1,
+    canc_timeout: float = 0.2,
+    tries: int = 3,
 ) -> int:
-    "Kill the actor-process with ``sig``."
+    '''
+    Kill the actor-process with `sig`.
+
+    Prefer to kill with the provided signal and
+    failing a `canc_timeout`, send a `SIKILL`-like
+    to ensure termination.
+
+    '''
+    for i in range(tries):
         proc.send_signal(sig)
-    time.sleep(canc_timeout)
         if not proc.poll():
+            print(
+                f'WARNING, proc still alive after,\n'
+                f'canc_timeout={canc_timeout!r}\n'
+                f'sig={sig!r}\n'
+                f'\n'
+                f'{proc.args!r}\n'
+            )
+            time.sleep(canc_timeout)
+    else:
         # TODO: why sometimes does SIGINT not work on teardown?
         # seems to happen only when trace logging enabled?
+        if not proc.poll():
+            breakpoint()
+            print(
+                f'XXX WARNING KILLING PROG WITH SIGINT XXX\n'
+                f'canc_timeout={canc_timeout!r}\n'
+                f'{proc.args!r}\n'
+            )
             proc.send_signal(_KILL_SIGNAL)
+
     ret: int = proc.wait()
     assert ret
 

tests/devx/test_debugger.py

@@ -785,17 +785,28 @@ def test_multi_nested_subactors_error_through_nurseries(
 
     # timed_out_early: bool = False
 
-    for send_char in itertools.cycle(['c', 'q']):
-        try:
-            child.expect(
-                PROMPT,
-                timeout=(
-                    6 if (
+    for (
+        i,
+        send_char,
+    ) in enumerate(itertools.cycle(['c', 'q'])):
+
+        timeout: float = -1
+        if (
             _non_linux
             and
             ci_env
-                    ) else -1
-                ),
+        ):
+            timeout: float = 6
+
+        # XXX linux but the first crash sequence
+        # can take longer to arrive at a prompt.
+        elif i == 0:
+            timeout = 5
+
+        try:
+            child.expect(
+                PROMPT,
+                timeout=timeout,
             )
             child.sendline(send_char)
             time.sleep(0.01)